Anyone know where the Aluminum plate is that Ocean factory puts in the deck for a fighting chair on a 1989 48 SS
Generally in the area you'd mount a SF, I don't know but it might be possible to see by looking underneath the deck with a mirror on a pole like the sell at the auto stores. Then just measure the distance of the extension pole from your location. You should see a raised portion on the underneath of the deck where the plate is in it.
I have a 55 and just installed a table in the cockpit. When mounting it I didn't notice any plates for a fighting chair. I simply made an aluminum backing plate and through bolted it.