I'm pulling the shaft this weekend on my boat, since loosing my prop at the end of the season, I figure the key banging against a loose prop may have cracked the shaft so I don't want to loose a brand new 541 (yup, another one) to a broken shaft for the sake of a quick dye check. Plus, the prop should be lapped, and doing that under the boat would be a pain. I can't speak to this as an expert, only what I've researched, and I would never consider installing a prop without lapping it after watching an expert explain how it should work.

http://www.youtube.com/watch?v=2ozh4JjoWm4