I've got a '03 3500 4x4 duramax/allison with 74k miles, the first u-joint behind the transfer case went bad & cracked the trans. Has anyone ever heard of such a thing???? When I took it to the dealer the tech said when that joint freezes it sets up a vibration that breaks the trans. They gave me an estimate of $8,000.00 to replace it. Chevy does not want to assist in the repairs (even though I think it's a design flaw) they said it's my fault, caused from the bad u-joint. Believe me it didn't take many miles once it was noticable.