Re: ? about painting my outdrive
If you're going to use a spray can don't waste your time and money with all the other prep. The spray can paint will stay on for a while, but it'll be no where near the equivelent of a professional 2 part paint. If you want it to last you need to use some kind of 2 part paint with a separate hardener.
If you'll be happy with the spray can results, just sand any rough spots and hit it with the spray can whenever it needs it.
If you want it to look factory, go here and follow the directions on "factory authorized repainting procedure" for an outdrive. Buying the smallest quantities possible of paint, alodine, etc, will set you back about $200, but you'll have enough to easily do 3 or 4 outdrives.
http://www.mercuryracing.com/techcorners/mercruiserfaqs.php#tech_11