Allison Transmission leaking between body and extension housing
Ive got an 03 2500HD with the 8.1/Allison. I believe the Allison should be more or less identical to the one that is in the Duramax trucks of the same year, so that is why i came here to ask my question.
So last weekend we drove 2.5hr towing a trailer with 2 ATVs and a Can Am SxS and when we got there the drivers side of the pickup had oil splashed all down the side and the trailer was starting to get some oil on it as well. The engine and trans oil were both at the full mark, so i assumed it was the transfer case. After i got back home and put the truck up on the lift most of the oil looks like it is coming from the gasket between the transmission and extension housing. the Transfer case is more or less completely dry. I have done some reading and found that to change this gasket it is best to pull the entire transmission and set it on its end to keep all the guts in. SO my question is, how likely is it that that gasket is leaking? Seems like an odd place to be leaking all of the sudden. I have read that is is more likely that the housing is cracked but i cannot see a crack anywhere on it. Up until now this truck has never leaked a drop, its only got about 110k miles.
What would you guys recommend doing? The oil is definitely coming from the back of the transmission, i just hate to go through all of this work to find out there is some simple common spot that they all leak from. My first thought was the dreaded transfer case pump rub, but like i said earlier its bone dry.
Thanks in advance.