1989 15hp Mercury lower unit seals.

[18Stingray]

I needed to replace the seals in the lower unit due to water getting in. Removing the gear housing to get to the prop shaft seal is there a proper way to tightening up that prop shaft housing? It seems if you bottom it out it makes the prop shaft tight to turn due to the fact that the gear rides on the back of it. Also if you remove the driveshaft from the gear case will that allow anything to fall out of place, along with the shifting rod? I put it all back together an everything seems fine, just figured I would ask now before its too late.

Thanks