How old is a Johnson outboard motor model number vxl-10s serial number 2398989?

I've just been researching this engine as I just bought a boat with one of these on the back on Sunday. I was told mine runs, but that it needs a magneto timing belt.

I've discovered thus far that this is a 1964 engine. I looked at a lot of exploded

views of similar engines around 1968 but I think that was because the parts

places I found on the web all started their lists at 1968.