2500hd with 8.1

coach03 · March 18, 2003

Is it possible to have another automatic tranny in this vechicle without it being an Allison? It is a 2001 with the big block 8.1,i bought this truck used with 10k miles and the dealer said it has the Allison. But it doesn't make all the different noise's that the Allison usually makes.Compared to others make that i have ridden in.

antig24 · March 18, 2003

The only auto tranny that comes from the factory for the 8.1L is the allison.

Roofer · March 18, 2003

I have to correct you slightly. The Avalanche 2500 with the 8.1 has the 4L85E.

But not available in the 2500HD truck.

BlackSilver · March 18, 2003

It's pretty easy to identify the Allison. Crawl underneath and you should see a spin-off fluid filter (looks like a small version of the oil filter on your engine) on the transmission.

By the way, my Allison is very quiet --- I got a video with the truck explaining that I might hear various transmission sounds under certain circumstances --- you have to listen VERY CAREFULLY to even hear a hint of those sounds on my truck. I consider that a "good thing"

CMNTMXR81 · March 19, 2003

2500HD's and 3500's with 8.1's and D-Max's only choice in automatics are the Allison.

Many a customer has complained about the Allison's noiseness. When we explain to them that it's a HEAVY DUTY truck transmission and it's gonna make a little more noise than a standard issue GM Hydramatic, they get the picture.

Mine sounds like a supercharger. I've had more people say "You've got a blower on that thing!"

coach03 · March 19, 2003

Well this one makes no more noise than previous GM auto trannies i have had?Like i said i have been in many others, that make all the ,and when you let off the go pedal it is like throwing out an anchor,not this one!Thanks for all the info,i will look under it to find the filter,when does it need to be changed?