I have a Ram 2500 4x4 6 spd auto 6.7L Cummins w/342 rearend. I get great milage around 17-18 unhooked. The question with this rearend I am limited to 9,775 lb. trailer. I am towing a trailer that weighs 9,520 and it hardly knows it's there. What damage would I do to the truck if I went to a 1200K 5th wheel? I always use tow/haul + exhaust brake and lock it out of 6th when towing. The trailer will probably would end up weighing about 11,500 loaded. Does anyone have any info on this. Thanks Mike

 

thoes are pretty tall gears for heavy towing, however if you not holding it too the floor from a stop, or being ruff with it, i dont think you will have a problem, but when doing thoes things, it is a very good idea to have a trans temp gauge to keep an eye on things