I am 1/2 done installing a 6.2 in an M37, I wanted comfort so I went with the 700R4 GM overdrive automatic. It is not heavy duty, but who works these trucks? The engine was installed using the chevy X member with motor mounts and bolted right into the dodge frame, the frame width is ground about 1/4" on both sides to clear the exh manifolds, the rear trans Xmember is again the chevy and bolts in by drilling 4 holes in frame as orig in chevy, the only hard part is the oil pan to diff clearance, I custom made an oil pan with a notch to clear the diff. The chevy Ovr Drv is cheap and readily avail. It is lighter then all the standards, no clutch linkage to worry about, the chevy steering column bolted in without too much trouble and then you have tilt wheel, signals, shifter horn etc. The trans case shifter bolts into the orig dodge t case hole if you turn it around. Can't wait until I have time to finish it!