Your Duramax-powered Chevy or GMC was built to tackle tough jobs with ease and deliver years of dependable performance. But when you push these trucks to their limits on a daily basis, reliability can quickly become a concern. While the engine is often up to the task, the factory transmission is usually the weak link—struggling under the added stress until clutches start slipping and failures begin. In many cases, a transmission rebuild or replacement is needed long before the engine shows any signs of trouble. And if you frequently push your truck to the max, even a rebuilt transmission may not hold up for long.

That’s exactly what inspired the development of the all-new DT Series STR Transmission. Designed for stock and mild-tuned trucks, the STR is built with key upgrades that stretch your budget further by maximizing durability and reliability. Whether you're replacing a worn-out stock unit or upgrading to gain a little more capability, the STR delivers the strength and performance you need to handle heavy towing and increased power from tuning—without the constant worry of another rebuild.

If you’re a Duramax diesel enthusiast or truck owner, you’re likely familiar with the Allison 1000 transmission. Revered for its durability, smooth shifting, and ability to handle the power of diesel engines like the GM Duramax, it’s a popular choice in heavy-duty trucks. However, even the best transmissions aren’t immune to problems. In this detailed guide, we’ll combine insights on diagnosing common issues, troubleshooting tips, and upgrading your Allison transmission to ensure your truck keeps running strong under any condition.

The Allison 1000 transmission has long been a cornerstone of GM’s HD truck lineup, particularly in conjunction with the Duramax engines. Over the years, this transmission has undergone continuous refinements to meet the evolving demands of power, performance, and emissions standards. In this post, we'll break down how the Allison 1000 transmission has evolved across six generations of the Duramax engine family: LB7, LLY, LBZ, LMM, LML, and L5P, highlighting key changes and comparing performance across each year range.

Diesel engines have many nuances when compared to their gas counterparts, fuel injectors being one of them. Unlike fuel injectors used on direct injection gasoline engines, diesel injectors often have a higher failure rate and shorter lifespan due to their more extreme operating conditions. When these injectors fail, it can lead to a cascade of performance issues, increased emissions issues, and even engine damage.

Over the years, GM has changed a lot regarding the turbos they use on Duramax engines. Not only have they changed manufacturers a handful of times but each RPO has its own unique measurements for key components. This can make it a headache when trying to track down exactly what the measurements of your stock turbo are. Luckily we've compiled this list of stock Duramax turbo specifications along with other helpful information so you can get a good idea of what you're already working with before you dive into the sea of turbo upgrades these trucks have to choose from. However, while some turbos may have the same peak power output, the size and shape of specific components can affect things such as exhaust gas temperature, drive pressure, and turbo efficiency range.  

As technology gets better, we see transmissions in trucks with more and more gears. Recently the Allison 6-speed was replaced with the 10-speed version. For older trucks, this can set them behind the competitors, both in terms of performance and fuel efficiency. A 6-speed conversion kit can take LB7 and LLY trucks to a whole new level of performance and drivability. 

If you are already in need of a valve body replacement due to slipping gears because of a weak or bad solenoid this kit is exactly what you'll want to swap in its place. The kit comes with an upgraded valve body combined with a 6-speed TCM. This upgraded TCM comes with updated shift schedules customized to your truck for the new gearing . Calibrated Power has been able to design one of the smoothest shifting 6-speed conversion kits there is. This kit will have your 15-year-old truck shifting like a 2018 model. It's also relatively simple to install and can easily be installed by someone who knows what they're doing in the shop or at home. Another option is to have Calibrated Power install it themselves in one of their upgraded transmissions (DT550, DT750, or DT1000), which is what you'll want if you're trying to make big power. 

If you're looking for any of these qualities out of your transmission then a 6-speed conversion is for you:

• Better MPG's
• Quieter Exhaust Drone On The Highway
• Smoother Shifting Transmission 
• Engine and Transmission Longevity
• Narrower Cruise Range to Meet Emissions Requirements

What's an RPO? Crucial Duramax Information!

This article will help you understand what an RPO is, how to find yours and when it will be needed.  An RPO or Regular Production Option is a GM-specific code, made up of 3 characters, that helps the manufacturer specify what configuration of options has been or needs to be applied to a vehicle. This can include anything from paint color to powertrain options. For Chevy/GMC Duramax trucks each type of engine can be signified by a different RPO code.

It’s common diesel knowledge that one of the weak points of the 2001-2004 Duramax diesel trucks is that the injectors will go bad. It’s something all of us LB7 drivers have had to deal with, the dreaded injector job. We’ve all been there or we are all about to get there.  First thing we will discuss is some of the issues you may experience when your LB7 injectors go bad.

The Six Speed Conversion Kit from duramaxtuner.com has been unleashed and it’s a proven winner.  The fifth gear days of yore have passed the world by and the 2001-2005 LB7 and LLY owners are loving how much more the extra gear brings them.  Large amounts R&D and testing has given 5 speeds a better shift schedule and the highest quality 5-6 and 6-5 shifts. The upgraded valve body with have your aging truck shifting like a new model.

What crashes an LB7 and LLY ECMs?:

If you have a 2001 - 2004 (LB7) or 2004.5 - 2005 (LLY) Duramax and have been thinking about tuning it, this article is for you. 

As you're probably aware, ECMs have some small risk of crashing during a tuning flash.  Browsing the forums online you definitely already picked up on the fact that the LB7 and LLY ECMs are more suscepitble to the issue.

To make sure you aren't stuck stranded somewhere far from home follow these tips: 

• Disconnect all aftermarket electronics
• Make sure your batteries are at a full charge
• Flash your truck at home or a local garage