In my '07 2500hd I have the 6.0 and 6-speed auto trans. I do not have the allison transmission. i was wondering if anyone knows where i can find a mild to medium shift kit for it. everything I've found so far is only for the Allison. And honestly I dont know the difference between the Allison 6-speed and mine. I truely beleive a shift kit improves the longevity of a auto trans, especially if you haul heavy loads on a regular basis. any help will be appreciated.

 

i dont know if there is a shift kit for the new 6l90e but you might look at either sonnax or transgo, they seem to the big names.

i would think the main difference between the allison and the 6l90 is strength and gearing. i believe the allison is still quite a bit stronger but im not sure.

 

Thought I'd give an update about a shift kit for the 6l90e. Apparently there isn't one. I've called TCI, they havent got around to it yet. Trans-go, they never picked up. Searched many a internet site and nothing. I did see a 6l90 in a 80s model truck and they claimed it was running round 590HP at the wheels and teh trans was stock and held up fine down the 1/4. Don't know if i beleive that though.

 

Look into a black bear tune. I believe they can change the computer programming for the trans to make it like a shift kit.