Many people spend a lot of time worrying whether they should buy a Duramax with an Allison transmission or not. This post will show all you need to know to help solve that concern. 

I have written this post as an unbiased review of all automatic transmissions since it is so hard for people to find trustworthy and accurate information about them online. 

Allison transmissions are the workhorse of truck transmissions. Thousands of applications have been developed based on their use, including everything from small dump trucks to 18-wheelers. Allison trucks are trucks equipped with an Allison transmission.

What is an Allison transmission?

Today’s Allison transmissions come in two main configurations: automatic and manual. An automatic transmission shifts gears for you, while a manual requires you to shift gears manually. Both offer efficiency and dependability as well as power.

Allison transmissions use advanced technologies that provide maximum durability, easy service and high performance. Allison has the right technology for your application, from advanced materials to fluid dynamic design concepts.

Trucks with the Allison transmission:

Allison transmissions are an excellent transmission to have in your truck. They have excellent customer support, and they are very durable. It is valid for all Allison transmissions but especially true for GM’s Duramax engines.

Trucks that come with the Allison Transmission:

Allison transmissions are an excellent choice since they can be rebuilt and have a reputation for being reliable over time. 

If you have one of these trucks, you should consider getting the Allison transmission rebuilt if you ever have to get one done.

  • All GMC trucks (except the Denali)
  • All Chevrolet Trucks (except Silverado Hybrid and Z71)
  • All Dodge Rams that do not have a Cummins engine

Allison transmissions are standard in all Chevrolet, GMC and Isuzu trucks from the Medium Duty (HD) lineup to the Heavy Duty (HD) lineup. You’ll also find Allison’s automatic transmissions in the Chevrolet Express, GMC Savana, and GMC TopKick medium-duty vans, as well as the Chevrolet Silverado and GMC Sierra light-duty pickups.

Trucks with Allison transmissions have a three-speed automatic that improves efficiency by providing quick response to driver inputs, optimizing engine performance over a wide range of conditions.

How Do I know if my Duramax has Allison Transmission?

It is essential to know if your Duramax has an Allison transmission. If it does, you can count on better fuel economy, smoother shifting and less downtime than those trucks with older transmissions. Tuning your Duramax will also help with improving your vehicle performance in the long run along with Allison transmission.

If you are considering the purchase of a new truck or are looking to upgrade the one you have, you will want to learn how to identify an Allison transmission. They may be hard to spot at first glance.

An excellent place to start is the rear of the truck. There should be two recessed lights on either side of the bumper. Dodge also uses these lights, so you can use this as a litmus test to see if it has the Allison. 

Tests like this are not 100% reliable, however, as some aftermarket add-ons will give your truck a similar appearance (if you are buying a used one, check for the VIN/SERIAL NUMBER! If there isn’t one, don’t buy it). 

To determine if you have an Allison transmission in your vehicle, look through the wheel well of your car and look for a 7-pin plug. The plug will have four pins facing forward and three pins facing back. If you find one, then congratulations! You have an Allison transmission!

Still, if you are not sure by looking at the engine block, I would suggest calling any of the following, as they should be able to tell you what transmission is in your truck:

GM Customer Service – 1-800-222-1020 (or 1-866-996-9463)

Allison Customer Service – 1-877-255-4171

International Duramax Diesel Association – 1-715-872-3881


Hopefully, we’ve been able to shed some light on how to identify what transmission is hiding under your hood. If you still aren’t sure, feel free to reach out to us with any questions. Remember: as they say, knowledge is power, and with these tools, in your toolbox, it will be easier than ever to tell what transmission you have behind your truck’s steering wheel.

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