The/your stern drive is an Alpha one Gen 2 drive designed to handle 300 HP on the high side of the spectrum. You have an engine rated at 350 HP so you'll want to be careful when accelerating and running at higher RPM as the drive could start to break down internally sooner than later especially since you have a bigger, heavier boat adding to the stress. You'll want to try and perform more regular gear lube changes to try and help preserve the drive unit.
Any idea of what engine was in there originally? The gear ratio "may" present an issue while trying to find the best over all performing propeller. So be cautious of that too.
Also know that there could be a rubber water pump impeller located between the upper and lower unit stern drive housings as Alphas use an impeller there when stock. Your engine model is/should say bravo on it somewhere? < That typically means the engine normally comes with a engine mounted sea water impeller pump. If so, depending on who installed the engine, some guys will leave one impeller in place, some will leave both in place and some will remove the impeller located between the drive housings and/or cut the intake water hose on the outside of the boat between the transom assembly and bell housing where the drive bolts on using the 6 nuts you see on the outside all in order to only use one impeller which is the engine mounted pump in most cases. If the outside hose is cut then usually someone will install a seawater pickup to the boats hull. Your mileage may very here but as service becomes needed, you will need to know what one/area to repair.
https://www.perfprotech.com/blog/articles/thru-hull-installation
The fuse missing will be the same yellow 20 AMP as the other 2.
The plug connectors you show are for updated smart craft features and digital trim gauges to sending units...Being a 1995 boat with most likely older model stock along gauges??? You wouldn't/shouldn't need to use them at this point.
Not sure why you have/show 2 serial numbers that started with 1G ?. Being a reman, you'd have to use the 1G number to id engine parts like I linked above but don't lose the 92502107 number as that would be for a Mercruiser dealer & factory use if/when needed....It's confusing I know but keep them both handy. Is the guy helping you Mercruiser trained? still working at a merc dealer? If so how long? Just some things you may want to know about him.
Item number 18 is located on the right/starboard side of the engine/boat when facing the bow. It's mounted to the exhaust manifold/riser. In both of the engine photos you can see the set/s ? of purple wires going to the shift cables assembly mounted on the starboard exhaust assembly. Is there one or two switches mounted to that shift bracket assembly??
A bravo drive uses one switch while an Alpha drive uses two switches like seen here,
http://www.mercruiserparts.com/Show...nbr=15322&bnbr=380&bdesc=Shift+Bracket,+Alpha
Being the engine is/was a bravo designed engine, it would have come stock with one switch...But since you have an Alpha drive unit, someone would have needed to install a newer model Alpha shift assembly that utilizes two switches on this MPI engine model in order to make the shift interrupter switch work properly. I'm just trying to help ensure it's the correct shift assembly due to the two different design models you seem to have. < One being a Alpha drive mounted to a bravo designed engine. If the shift interrupter switch isn't connected or adjusted correctly then the engine won't start due to no spark as the shift interrupter switch is designed to interrupt spark during shifting out of gear on the Alpha stern drives for a very short timeframe.
Your engine model running,
https://www.perfprotech.com/mercrui...obtail-marine-engine-865108r80/product/188707
Where are you located?
