The biggest differences I am aware of to watch out for in a motor swap are the new style rear mount bushing and the new style wiring harness on late model MCM motors:
- Mercruiser eliminated the spiral spring in the rear mount bushings in 2003 and changed the height slightly - that means the height of the fwd mts may change a little. Mercruiser service Bulletin 2003-11.
- I can't remember when they went from the 9 pin round harness connector to the 14 pin connector but there adapters for that.