I'm looking at an 02 avalanche with the 8.1L. I saw the the RPO code is supposed to be M74 for the allison transmission, but the guy who's selling it cant find that code anywhere in the glove compartment. He also couldnt find the code MT1 for the 4l80e. Are we looking in the right place? Whats the easiest way to tell what tranny the avalnche has? which is the better tranny? thanks

Chad

 

See if the tranny has an external filter. I think the Allison has an external spin-on filter. That could tell you right there.

 

I think the allison says ALLISON on the trans pan. You might check that.

 

well you can look under the truck and if you see the red spin-on filter its the allison. If it has a longer than normal tranny pan it should be the 4l80e. If you have the vin for the truck shoot it to me and ill look it up for you.

 

ok, thanks for the info guys. The truck that i am looking at is in another state, so i will try to talk him into looking at the tranny for an oil filter. If not, ill hit you up on your offer chevymec.

Chad

 

just shoot me a pm if you get the vin.

 

I'm pretty sure the avalanche 2500 with 8100 only has 4L80E available.

 

The allison would be more heavy duty of the two..I dont thank you can get the allison with the 3/4 ton avalanche..But,I could be wrong.. It should say allison on the transmission pan if it has one..This picture might help..

 

The 2500 Suburban, Avalanche, and Yukon XL with the 8.1 all get the 4L85-E transmission. The Allison requires a body lift - this would compromise ride, handling, comfort and accessibility on an SUV considering what they are mostly used for and who they are used by.

 

Whats a 4l85e??