I have a 96 5 speed with somewhere around 400+H. P. I am towing a 35' triple slide fifth wheel weighing 15-16000 lbs loaded. After eating my stock clutch I installed a luk dual friction clutch,this lasted about 3 wks (cooked). Installed the full ceramic version and this held great,although it was terrible for backing the trailer up (too much chatter). Other than both my wife and I having to learn how to drive all over again with a ceramic clutch,it was a pretty good set up. Then recently we were towing up a long hill at about half throttle in 4th gear when 30 seconds later I snapped my input shaft. My wife has started complaining that every time we go on vacation we are having breakage. Iam wondering if anyone has installed a 6sp Allison or 7sp Eaton I want to build a drivetrain out of a bus or larger truck that can handle the torque that these engines can produce. If anyone has done this how difficult and expensive is it and what kind of rpms do you run on the highway??