Sorry for such a late response to this.
I have a 1997 50HP and note the comment from
@racerone that my lower unit is not the most rugged one out there, so this post intrigued me because I may one day find myself with a failed lower unit, and from what I see online, the older 1975-1988 lower unit is more reliable and easier to find a replacement for than the 1993+ lower unit.
If I read this thread correctly, it sounds like you have swapped an older lower unit from an 1988 model (with the 4 water inlet holes on each side) to replace a 1995 40HP lower unit (with the inlet screens on each side.)
If I continue to read this correctly, you accomplished this by removing the driveshaft from the 1995 lower unit and installing it on the 1988 lower unit, installing the correct shims to make it work.
Did I read this correctly?
Photos attached..
1998 40/45/50HP
Removed per
@racerone id.
1995 40/45/50HP
70HP