Re: prop shaft
Okaye, if my memory serves me, there are two screws holding the bearing retainer in place, one on top and one on the bottom......immediately in front of the prop. Pulling them allows you to pull the bearing retainer, shifter shuttle, reverse gear, prop rear bearing, seal, and prop shaft. The F gear remains in the housing due to the drive gear mounted to the drive shaft.
I don't think Merc used the old style locking system with it's V engines, but if it did, pull the prop, look on the inner surface of the lower unit housing and you will note it is threaded. Looking further into the lower unit you will see a spanner nut that is threaded into these threads...has 4 tangs on it for removal/installation. Removing that nut allows the same parts to be removed.....Usually the threads are corroded and the nut is almost the diameter of the gearbox so removing this one is a real chore if it hasn't been recently removed, which it usually hasn't and salt water corrodes the housing and makes it near impossible to remove.
Mark