it is the alison automatic transmission. The problem is that when accelerating from a dead stop it slips so bad when you get right around 40mph that its like you turned the key off. Let off the fuel a bit and it hooks back up and keeps going. Its only when accelerating from a dead stop, not when just slowed down and stepping into it. Figured it would be a good time to just get the whole thing gone through and rebuilt with how many miles are on it. I have a post in the towing forum about it.