So I just removed that similar piece from a 1963 75 johnson. It took about 2 days and I destroyed the plate. (part #42) so I had to order a new one from the link provided above. That thing had been in there since 1963 and wasn't coming out. What I did was drill enough holes to break pieces of the plate off, however the round part at the bottom is almost "pressed in" so once I got the square part off, I had to do the same hole drilling process on the round part. you have to be VERY CAREFUL not to drill into the case though. It took time and a lot of patience, but I latterly just got the new one in yesterday with some new bearings and seals. It's no longer leaking gear oil or water into the gear oil. Good luck!