Building a fresh frame for the next project (1/2 ton 2wd) consisting of a 75 frame and a 77 front crossmember. I went to bolt the motor mount plates to the frame and crossmember and the holes do not match, almost 1/2 inch off (just short of aligning) on the crossmember given the top side is bolted to the frame. I have motor mount plates from both a 3/4 ton and a 1 ton and neither fit. Is the motor mount plate unique to the 1/2 ton before I make a trip to the bone yard??? The rails are straight and is a no hit frame.