I have a Manual transmission and a Mcloud clutch, approx 45,000 on the clutch. Today while towing a 10,800 5th wheel in 3rd gear at 1900 rpm and about 28 mph going up a 3% grade. My truck was in the sweet spot. Then while thinking how bullet proof my truck is, the quote "golden BB" hit. I felt and heard a loud noise, similar to breaking a driveline. I was able to get to the side of the road and saw no nuts and bolts down the road. Underneath the truck is clean, the truck will start and will start in gear but it shutters and vibrates and will not go. Each time I start it (twice) the vibration and shuddering is bad. I have been towed home trailer and all. I am thinking transmission or gears or something. I dont know what it may be cause I have seen my truck apart and it does not seem like to much can go wrong. Any diagnosisis? Thanks