Mercury Lower Unit Compatibility?

[WTBonthewater]

I have a 1982 Mercury 200 Black Max. The motor runs great but the lower unit is banging once or twice when I first accelerate. My guess is it is time for a new one? or maybe its not shifting fully into gear? When looking for a new/used one will others fit of different size ones like a merc 150 and of other years like say 1989?Other models? .....My lower unit has a preload pin at the top of the shaft, will others that do not have one work??
------Thanks in advance for all the advice.

[Specialized P4-12]

yeah.. you can run a non preload lower unit... just make sure it is not from a 3 liter and not an inline six... any v6 2.5 2.0 or 2.4 preload or non preload will bolt right on... the non preload lowers will hold up better in the long run.. as for the old one check your adjustment and make sure its not just ur shifter that is out of adjustment.. if it is fine then u probably got some issues internally.. i dont recomend getting into taking it apart unless u have the tools..