That ‘seal’ is probably no more than an o-ring or more probably packing. The sealing system on these is marginally better than plain bushings. Johnsons used lipped seals, while these used compression, caps, and packings. Best to pay attention to regular lubrication, and hope that the previous owner did, too.
I guess I’ll need to tear into it to get a better idea. I was able to find a NOS gear case, so I’ll need to transfer the parts from several different cases. My old case was leaking and all the gears rotted away and messed up the bearings. Another case was cracked. I was going to have it welded until I found this NOS case.
OK I was able to get the seal from MarineEngine.com. Question, how tight do I make the bushing (pressed fit), and how do I know how tight I’m making it? Also, what type of lube do I use on the shaft bushing and seal?