There is one vent plug and one drain/fill plug. Take anything else out you are in deeeeep trouble.
TIP: Get a Service Manual; anyone who works on an outboard without one has a fool for a mechanic.
The hex on the very bottom is the drain. Mine was so tight, I said, ok! here goes and gave the allen wrench everything I had while tapping on it with a hammer. It gave. Was prepared to drill and tap. Cleaned threads, inside and out,(tap and die set) used antiseize when reinstalling.
Scary!
I might as well jump into this thread seeing how I have the same lower unit.
I think some of the confusion is that we have a DIFFERENT lower unit then upper unit, quite often people slapped 89' Mercury lower units on there.
Either way that picture is correct, the big screw closest to the facing front is the fill the other one is the vent
I have a question about the drain on mine though, I'm leaking gear lube out of it! Is there a screw or something that's suppose to be in there or a gasket?!? ack