GMC 2500 HD Duramax diesel with Allison transmission. Strong engine and transmission…. Unfortunately, there is an electrical issue external to the transmission…. Transmission often gets stuck in gear…. I have taken the truck to bullfrog to confirm this and have code readout…. if you are knowledgable with electrical issues it would probably be worth fixing. I was daily driving it up until a little while ago could probably use ball joints, tie, rod ends, and brakes….