lower unit interchange

[crappiehuntr]

I have 1975 50 merc 4 cylinder and was wondering what other lower unit years and hp will fit. I dont have a prop yet so if the gear ratio is different thats ok if everything else works thanks also how do you tighten the motor up its a tiller and it spins freely on the mount.

[boats.net]

It looks like just the 402 and 50 model used that gearcase.