Not sure what version of the 40hp that your friend has, but I did my 40C (2cyl 2 stroke) last year. It was very simple and very similiar to evinrude/johnsons I've done. While I didn't have any issues, you can see by a few posts here, that getting the lower unit off, is most of the battle. I don't remember any special procedures, but I did have a manual, and I did a pump kit replacement, not just empeller. <br /><br />PS: I did my first mercruiser pump kit, a few weeks ago. Very similiar to the outboards as well, just bigger and heavier.