I just added a Jake Brake on my 06 2500 Ram diesel 4x4 with auto tranny. Love the brake when towing the 4 wheelers and the toy hauler, but only had it on 3 weeks and the tranny went out. Ask Jacobs if the brake could have caused this and they said no-way of course. I really don't dought them but just thought I'd throw this out there to see if anyone else has ever had the problem. I don't tow that often, and the tranny gave me no warning at all. No slipage at all, just got in it one morning and it would not shift out of low gear. Having it rebuilt right now , and I'm beefing it up with larger torque converter, stronger bands (oversize I think) and a couple shaft enlargments.
Hope this solves the problem, by the way I had 120,000 miles on her when she went to the hospital. Absolutley love this truck, but they all have problems.