Diesel pickup trucks are great. You get enough power and capability to practically haul mountains in a package that could be your daily driver. While Ford, General Motors, and Ram each sell hundreds of thousands of new trucks each year, some truck enthusiasts prefer the pickups of yesteryear. Many Ford and Ram fans go back more than a couple of decades for their Holy Grails. For GM, many diesel fans look to newer, more modern trucks, but not too modern. The 6.6-liter Duramax LBZ produces modern power and is backed by a solid Allison 1000 transmission, and it’s known as the last GM diesel to come without the reliability complications brought on by modern emissions controls. Here’s why people are willing to pay tens of thousands of dollars to get their hands on trucks sold from just 2006 to 2007.
Back in November, I wrote a special edition of Holy Grails about one of the greatest truck engines of all time, the legendary Cummins 5.9-liter 12-valve straight-six diesel. It’s not hard to find a clean two-decade-old truck with one of these engines with an asking price greater than some new cars. For just half of 1998, you could get the Ram 2500 Quad Cab with a 12-valve Cummins and a manual transmission. This combination appears to be so rare that it’s easier to find million-dollar limited-production supercars for sale.
In January, I then wrote about the trucks Ford fans adore. Another truck engine with about the same fame as the Cummins 5.9 12-valve is the Navistar T444E, also known as the Ford 7.3-liter Power Stroke. Like the Cummins, this engine is known for its practically bulletproof durability, lack of complicated systems, and tuning potential. While it appears there is no one true Holy Grail of Ford diesels, you were able to option a Power Stroke truck with a manual transmission, four-wheel-drive, locking hubs, and glorious purple paint.
However, there is probably something you’ve noticed during my diesel truck history saga: These are some old rigs. The newest Ford 7.3-liter Power Stroke truck is 21 years old and the newest Cummins 5.9 12-valve is 26 years old! If you’ve ever sat in or driven a second-generation Ram before, you’ll probably agree with me that those interiors aren’t exactly a lovely place to fit in. The Fords are better, but you’ll never forget that you’re driving a ’90s truck.
That’s where General Motors comes in with what many enthusiasts call the Holy Grail of Duramax trucks. The 6.6-liter Duramax LBZ was sold between 2006 and 2007, landing it right at the end of the first-generation Chevrolet Silverado and GMC Sierra 2500HD and 3500 models. Not only do you get another fantastic GM truck platform, the GMT800, but a truck with a more modern body and interior than the older Ford and Ram diesels.
General Motors Diesel
For decades, General Motors was essentially an unstoppable force in diesel power. GM’s diesel power dominated the locomotive industry and its engines even found homes inside of the heavy trucks of competitors. Chances are, your life has been impacted by some sort of vehicle with GM diesel power, be it a train you’ve taken, a bus you hopped on, a ship you’ve ridden in, or the fire engine that put out the fires from your hot takes. GM hasn’t always produced the most powerful diesel, but it’s hard to put into words how much of America has moved under GM diesel power.
GM’s history with diesel starts with another name, Alexander Winton. As MotorTrend writes, Winton came to America from Scotland in 1878. In his early years in America, Winton followed in his father’s footsteps by becoming a marine engineer on oceangoing ships. He also did a stint in Cleveland, Ohio’s iron ore processing industry at the Delameter Iron Works.
Like many automotive and motorcycle pioneers of the late 1800s, the increasing popularity of the bicycle caught Winton’s attention. In 1891, Winton founded the Winton Bicycle Co. and found success in selling bicycles. It wasn’t long before Winton, like other engineers of the era, started seeing carriages and bicycles as vehicles that could power themselves. By 1896, Winton created his first motorized carriage and founded Winton Motor Carriage Company the next year. Reportedly, Winton was so good at making early cars that it was only in 1898 that his Winton Six was considered to be the most advanced and the most powerful American car on what passed as roads back then. A Winton car even drove from Cleveland to New York City, taking nine days to complete the task.
Winton was also one of the first people to make a recorded sale of a car when in 1898, he sold a car to Robert Allison of Pennsylvania for $1,000. Reportedly, he also created one of the world’s first semi-trucks in 1898, two years after when Gottlieb Daimler is said to have built the first truck. Winton was also an avid racer and earned a reputation as one of the era’s great drivers. As the Cleveland Center For Public History writes, it is rumored that Winton was even the inspiration for another great American car brand. As the story goes, Winton sold James Ward Packard a car and Packard wasn’t pleased with the Winton’s power and quality. Packard complained to Winton, who issued Packard a challenge to build a better car. Packard then founded his own company and I don’t have to tell you which company is better remembered.
Another story mentioned by the Cleveland Center For Public History is that of when Leo Melanowski invited Henry Ford to work for Winton. Allegedly, Winton wasn’t impressed with Ford and passed on the opportunity. In 1901, Ford decided to challenge Winton to a race. Of course, Winton was famous for racing, so the odds appeared to be in his favor. Winton’s car was indeed faster than Ford’s, but Ford’s car was more reliable, ultimately allowing Ford to take the win. Ford raced Winton again later, but with a driver, taking another win. Ford proved himself enough in racing to secure funding for his own car company.
The Cleveland Center For Public History notes that these events would eventually haunt Winton. But that didn’t stop Winton, as he continued stacking patents to his name. In addition to improving car brakes, Winton’s and his Winton Gas Engine & Mfg. Co. began work on creating diesel engines. In 1913, Winton took Rudolf Diesel’s engine design and turned it into what is reportedly America’s first diesel engine. The company became the Winton Engine Works in 1916 and it began making engines for ships and later, locomotive engines.
Over at General Motors, Charles Kettering had run a diesel development program since 1928. One of Kettering’s first diesels was the four-stroke 175 HP engine that powered his 105-foot yacht. Kettering wasn’t pleased with the rudimentary injection system and the performance of his diesel, and looked to develop a better two-stroke engine to sell to railroads. Unfortunately, the railroads weren’t interested. General Motors determined that it would be easier to just buy companies that specialized in diesel engines. In 1930, GM purchased the Winton Engine Company and the Electro-Motive Company, known back then for building self-propelled railcars.
Kettering joined engineers from Winton, Electro-Motive, and GM Research to design better, more powerful diesel engines. The engineers even toured Europe to see what was hot over there. At first, GM’s diesel two-stroke engine development showed promise, but the greatest interest came from the Navy for use in submarines.
At the 1933 Century of Progress exhibition in Chicago, GM caught the attention of Ralph Budd, the president of the Burlington Railroad, who wanted to use diesel power to whisk passengers to far-flung destinations. GM’s divisions worked together to create the firepower behind the majestic Zephyr streamliner trains.
With successes under its wheels, GM created the Detroit Diesel Engine Division in 1938 while the Winton Engine Corporation became the Cleveland Diesel Engine Division. Cleveland’s focus was on marine and locomotive diesels while Detroit introduced its flagship engine, the Series 71. There was some overlap there as Detroit Diesels were bolted into road vehicles but also found marine applications as well.
Detroit diesel powerplants would find themselves lowered into all sorts of heavy equipment for decades, but it would take a while before you could find one in a pickup truck.
Demand Detroit
Let’s fast-forward to the 1970s. General Motors has a dominating grasp on diesel in heavy vehicles, but one area GM hadn’t entered was the diesel pickup truck.
Dodge first experimented with a diesel pickup in 1962 with the Dodge W300. International Harvester had its own diesel pickups at about the same time as the C-1100 to C-1300 trucks. At the time, diesel was gaining traction in the medium-duty space and IH thought people would want diesel power in light-duty trucks. It isn’t known how many examples International Harvester and Dodge sold, but those early diesel pickups are far from common.
In the 1970s, the idea of powering trucks with diesel engines returned and multiple manufacturers began exploring light-duty diesel applications. Of course, American drivers faced multiple oil crises and a general tightening of their belts. Thirsty trucks and cars were no longer in vogue, and diesel engines promised better fuel economy.
In 1978, Dodge saddled some D100s and D200s with Mitsubishi 6DR5 sixes, engines that made less power than an equivalent gas engine. That year also marked the beginning of production for the Oldsmobile Diesel.
If you don’t know about the Oldsmobile diesel, let’s take a short detour to take a look at GM’s effort to meet CAFE standards. It’s often said that to make its infamous diesel engine, GM’s engineers just converted a gasoline V8 engine to run diesel. The truth isn’t that silly, but it’s still pretty bad. Reportedly, the Oldsmobile diesel’s development was done on the cheap, leading to aggressive cost-cutting. Engineers were forced to stick to the same bore, stroke, and number of head bolts as the 350-cubic-inch gas V8 the diesel would borrow architecture from. This meant that GM could produce both engines without changing tooling. Also bad was the lack of a water separator, which was needed back in those days because American diesel often had water in it.
If all of that sounds bad, the reality was somehow even worse. The engines often blew gaskets because as you could guess, the ten head bolts that kept the gas engine together couldn’t withstand the higher pressures of a diesel. As the New York Times reported, cars equipped with Oldsmobile diesel V8 weren’t approved for sale in California not because of emissions, but because the engines were so unreliable that they couldn’t survive California’s state tests without breaking down. Reportedly, all nine of California’s test cars had engine problems while seven had transmission problems on top of the engine woes.
Allegedly, Darrel R. Sand, an engineer of the Olds diesel V8, was sacked after complaining that the engine’s development was rushed, leading to issues so catastrophic that 10,000 people across 14 states demanded a uniform redress program from GM. Others launched three class-action suits against GM, too.
It’s been said that the Oldsmobile diesel V8 sucked so much that it singlehandedly killed the interest in diesel cars. Thankfully, it didn’t kill interest in diesel trucks and at first, half-ton C-series trucks were able to be ordered with the Oldsmobile Diesel. Once again, the diesel wasn’t for power but for fuel economy. These were engines that made just 120 HP and 220 lb-ft of torque, getting downgraded to 105 HP by 1981. This was illustrated by the fact that diesel-equipped pickups had a lower tow rating than their gas equivalents. But it was a start.
In 1982, GM’s pickups got a major upgrade when the 350 Olds Diesel was canned in favor of an indirect injection 6.2-liter diesel V8 developed in collaboration with GM subsidiary Detroit Diesel. The four-stroke 6.2-liter V8 was a different kind of engine for Detroit as it mostly focused on large two-strokes for buses and trucks.
Reportedly, this engine was once again designed more for fuel economy than power. As a result, at launch, the engines made a whopping 130 HP and 240 lb-ft of torque. So, the engines were totally gutless, but they were capable of 15 to 20 mpg depending on application, making them less thirsty than Chevy’s 4.3-liter six. The mechanically-injected 6.2 Detroits also gained a reputation for easy gas-to-diesel engine swaps.
Unfortunately, General Motors was a little behind the curve. The same year that GM began production of the Detroit 6.2 V8, International Harvester released the IDI 6.9-liter diesel V8, which made 170 HP and 315 lb-ft of torque. By 1989 The Dodge Ram hit the deck with the B5.9 Cummins, which made 160 HP and 400 lb-ft of torque. IH and Cummins worked on increasing power from its diesels, leaving GM in the dust. It didn’t help that the 6.2 Detroits had issues that included overheating, broken cranks, cracked heads, trouble starting, and more.
GM and Detroit Diesel had to do something, and in 1992, the improved indirect injection 6.5-liter Detroit Diesel V8 was released.
At launch, turbo models made 180 HP and 360 lb-ft, bringing it closer to competition with Ford and Dodge. This engine, while still subjected to some of the above issues, sold until 2002, and power maxed out at 215 HP and 440 lb-ft of torque. Sadly, this still lagged behind. Late model 7.3-liter Power Strokes made 275 HP and 525 lb-ft of torque when attached to manual transmissions.
Birth Of The Duramax
Before the 6.5-liter Detroit ended production in 2002, General Motors was already working on a successor. In 1997, General Motors and Isuzu entered into a 60-40 joint venture in a new company called DMAX. Detroit Diesel was also sold to Daimler Truck North America in 2000. Together, the companies worked to create America’s first common-rail, direct-injection diesel truck engine. Not only would their engine be a technological leap forward with the aforementioned technologies, but it would hit the ground running with 300 HP and 520 lb-ft of torque, finally putting General Motors past Dodge and Ford’s entries.
The 6.6-liter Duramax LB7 made its debut in 2000, finding itself saddled in 2001.5 three-quarter and 1-ton trucks. Along with a Bosch high-pressure fuel system and direct injection, those early Duramax engines featured aluminum heads, a fixed-geometry turbo, and 32 valves plus a cast-iron block.
In 2004.5, the 6.6-liter Duramax V8 evolved into the LLY, which boosted power to 310 HP and 605 lb-ft of torque. It’s noted that the LLY marked the beginning of real emissions controls in these engines, and they had a variable geometry Garrett turbo and an EGR valve to help lower emissions. Another improvement was the ability to access the engine’s injectors without having to remove the valve covers.
These engines were placed into another one of GM’s famous truck platforms, the GMT800. The successor to the legendary GMT400, the GMT800, which launched in 1999 added some notable improvements. One headlining change was a three-piece frame as opposed to a single-piece frame. Having the frame in sections allowed GM to mix frame parts to match specific configurations for truck GVWR, wheelbase, and body. The front section of the frame was hydroformed, while the middle and rear sections were roll-formed or stamped depending on the vehicle. Bolted to the GMT800 frame was an independent suspension up front and leaf packs in the rear. You could also get your diesel 4×4 trucks in manual if you want, but I suspect automatic was the more popular option.
The excellent frame was only part of the equation, as GM fitted these frames with modern truck and SUV bodies as well as a variety of powertrain options ranging from gas engines and diesel to a CNG engine and a hybrid. Some people believe the GMT800 was and remains one of the greatest truck platforms of all time for its honest reliability, affordable parts, user-friendly repairs, and longevity. Reader Shop-Teacher has a beautiful GMT800 and I’m convinced it’ll outlive all of my Volkswagens.
While you really couldn’t go wrong with almost any GMT800 truck, one stands out as being called the Holy Grail by many enthusiasts.
The LBZ Duramax
For 2006 and 2007, the last years you could buy a new GMT800, General Motors hit a home run with its Duramax engine.
See, while the LB7 and LLY Duramax engines are good, diesel resource websites note that they had a few issues that keep them from being truly great engines. The LLY has a list of common issues from overheating and water pump failures to glow plug issues and bent rods. The latter is noted to be an uncommon problem with stock trucks, but happens more often with tuned rigs. Another notable issue is a blown head gasket and reportedly, it’s not just because of overheating, but because of the engine’s apparently inadequate cooling system.
Mechanically, the LBZ is similar to the LLY, but with a thicker engine block casting, beefy forged-steel connecting rods, and the common-rail fuel system was turned up even higher with a Bosch CP3 fuel pump. That fuel pump is so powerful that it’s capable of moving 200 liters of fuel per hour. Other upgrades include more webbing in the main bearings, taller main bearing caps, and the bores for those cap bolts dig 4mm deeper before. In other words, GM went through the faults of its previous Duramax powerplants and hardened them.
But GM didn’t stop with making a more reliable engine, as engineers found more power in the Duramax 6.6-liter V8. The previous engine had a bottleneck on the compressor side of the turbo. GM fixed that with a larger turbo inlet manifold. As a result, the turbo also lost lag. Additional changes come from injector pressure increased from 23,000 psi to 26,000 psi, a larger EGR cooler, and new seven-hole Bosch solenoid-style injectors. The engines also utilized oil-spray cooling at the bottom of the piston bowl to help keep the engine cooler. Out of the other end of the changes, buyers got 360 HP and 650 lb-ft, power that’s still more than healthy enough for current-day duty. Oh, and it stomped its Ford and Dodge contemporaries.
For owners and tuners, one important fact about the Duramax LBZ is that it’s the last pickup diesel from GM to come without a diesel particulate filter, which is known to sap fuel economy from the LBZ’s successor. DPFs can also fail, causing expensive repair bills that can sideline an otherwise perfectly good truck. Another benefit is that LBZ-equipped trucks were paired with an Allison 1000 six-speed automatic, a unit known for its durability. Trucks with the Allison 1000 can cruise at 60 mph at just 1,550 RPM.
For GM diesel truck fans, just about any 2500HD truck featuring the short-lived Duramax LBZ and that Allison 1000 is a Holy Grail. It’s unclear how many of these trucks were sold, but remember, they were sold from just 2006 to 2007, which is pretty short in truck time.
In addition to the Duramax and Allison combination, GM’s 2500HD trucks packed a punch. They boasted a payload of up to 3,317 pounds and 9,800 pounds of trailer towing. You could also get your heavy hauler with four-wheel-drive and four doors so the whole family can ride. Interior options included OnStar, heated mirrors, dual-zone climate control, keyless entry, heated seats, leather, power seats, forged aluminum wheels, lumbar support, and more. In other words, we aren’t talking Mercedes-Benz levels of luxury, but the GMT800 2500HD trucks had more than enough gear to be a family hauler during the week and a toy hauler on the weekend.
It should be noted that the LBZ isn’t entirely bulletproof. Pistons are cast aluminum, which are said to work fine for stock trucks, but can become problematic when you pile on the power. Larger injectors and turbos can cause the pistons to crack. Another common issue is the variable geometry turbo sticking, an issue some diesel Volkswagen owners also know very well. Factory water pumps, which have plastic impellers, are also known to fail with age and mileage.
So, now we come to the bad news. These trucks are insanely popular. Unfortunately, that means finding a stock one is difficult and the trucks you will find will often have asking prices of about $15,000 for high-mileage examples and $20,000, $30,000, and sometimes higher for clean low-mileage examples. Owners report paying $40,000 or more for these trucks when they were new. It’s believed that GM made somewhere around 200,000 Duramax trucks a year, so these trucks are only rare compared to the millions of trucks that end up sold normally. But you shouldn’t have a problem finding one.
It’s easy to see why people are all over these LBZ trucks. As someone who loves modern diesels, I know the pain of paying to maintain expensive emissions equipment.
Whatever money you save on fuel can easily be erased by replacing a broken DPF. Emissions equipment failures can even put a diesel into a low-power state, a bummer if you’re on a road trip and trying to haul a trailer. Buying one of these older diesels avoids all of that stuff, while still giving you modern power and tuning potential. Just, please don’t be one of those people who turn their trucks into devices to blow black clouds into Prius drivers and cyclists.
This completes our history on the mighty coveted diesels of the Big Three. There are other great diesels out there and we may cover them in the future. There was a time when diesel was thought to be the future, now diesel has returned to just being equipment for trucks. One day, these mythical truck engines will be old-school technology destined for the history books, so if you’re a fan of diesel trucks, enjoy them!
Do you know of or own a car, bus, motorcycle, or something else worthy of being called a ‘holy grail’? Send me an email at mercedes@theautopian.com or drop it down in the comments!
I bought mine in 2017 and I’m not ashamed to say I paid $35k cash for it. 45k miles, dark blue metallic, 4×4, crew cab , fully loaded, plus it already had air bags. I wanted a truck to haul my cabover or tow a camper if I upgrade one day. I was pricing new trucks at the time and something comparable would have been double the price. Only clocked 25k miles since I bought her so at my age it’s likely the last truck I’ll ever buy. No regrets.
After a long hunt I recently nabbed an early 2007 2500HD with the LBZ. Took me a while to find the configuration I wanted (4×4, Crew Cab, Long Bed, Front Bench, Grey Interior, White Exterior, etc.). I wanted something that was unmodified (no tune, exhaust, lift kit, etc.) and as long as it wasn’t abused and was well maintained the miles didn’t scare me too much.
Last November I found the exact truck I was looking for 500 miles away. It had higher miles (~240k) but it had been a CA truck it’s whole life and the original 73 y/o owner babied it and had service records since new… You could tell he really cared for the truck and was actually asking a reasonable price.
I’ve been a diehard Toyota guy my whole life, but sold my 2015 Tundra Limited to get the LBZ and have no regrets. The GMT 800 platform is modern enough to be comfortable and reliable, but it’s still simple, easy to work on and when something does break parts are plentiful. I also love how much smaller / manageable it is than the newer 3/4 & 1 ton options from the big three.
When I asked my wife what she thought about it she replied “there’s something loveable about it… it’s just an honest truck” and I couldn’t agree more.
The writer of this article is surely banking on someone’s DPF to go out. There’s millions of trucks on the road with them and only a small % of them have issues
A small diesel, running at a near-constant speed, might be a winner for peak efficiency when coupled to a large battery pack, similar to the Stellantis Ramcharger.
You just described a diesel electric locomotive
GM is now “flying on its own” for diesel development and manufacturing, having divested themselves of their equity investment in Isuzu, and now owning 100% of what was formally their joint venture with Isuzu (DMAX) in Ohio. Compared to the Detroit three, GM remains the most committed to diesels, offering both heavy duty and light duty versions, with a new larger V8 possibly on the way.
very good historical write up.
Yea I’ll take a 12 valve Cummins or 7.3 any day over that Isuzu pos. Selling for prices like new? My first gen in disarray is worth what it sold brand new. Cab swap and paint and its worth 4-5 times more than what it sold brand new.
Isuzu is the one to thank for these trucks’ reputations.
You also don’t see that many left because they’ve rusted away.
They also have the oft-overlooked situation where the pedals, wheel, and driver’s seat are on different planes, almost like a kit that was built from three different sets of instructions and crammed together (probably fairly accurate, knowing how gm loves its design committees). GM trucks up until the 2014+ models (IIRC) kill my back to drive more than a few minutes at a time because while sitting centered in the seat the steering wheel and pedals are inboard of the driver. It’s maddening. And as I’m aging it’s started to mess with my hips, knees, and ankles, too (our work plow truck is a 2011 Sierra, and I’m all too familiar with them).
At least with vehicles with similar inboard-located controls (Lamborghinis come to mind for the most well-known ones, especially the Countach) the seat is angled slightly to match the wheel and pedals (but with a tiny pedal box, because there’s mechanical parts on the opposite side of the floor pan). So while you in the cabin are traveling slightly sideways instead of straight-on, at least your limbs and spine should be aligned with each other.
Peak diesel GMT800 for sure, they surely are sought after. IMO a pretty nice alternative is the 8.1L & Allison auto. My brother has one in LTZ crew configuration and could tow nicely and they’re a reasonable cost for a nice unit.
So many GMT800 variants made between trucks/SUVs. There needs to be an article on that in itself!!!