I have been a member here for many years picked up a new project Wednesday. 1993 ram 150 short bed 2 wheel drive. 3.9 v6 auto trans 74k original miles. The previous owner removed the doors fenders hood and bed and did a complete color change to black had all the trim and emblems removed and the holes welded up. He had a financial emergency and needed cash. I want to remove the 3.9 and install a 383 big block. Every engine swap kit I find specifically says will not work with factory 3.9. Anyone know why? And where I might be able to find some mounts?