Do the external parts of the 4.2 and 4.0 match up? I have a 4.2 beyond rebuilding so I wanted to see if I could replace it with a 4.0 short block. Will the 4.2 timing cover, water pump, oil pan and AX15 transmission adapt to the 4.0? I don't have the knowledge of this swap, so any help would be greatly appreciated. I'm ready to trail ride! Also have HEI, want to keep that.