i have a 1966? jd 1020. it has a oil pan drain plug like i have not seen before. it looks like a 8 sided allen wrench around 9/16. it looks original. has anybody seen this.
The 1950s-70s 10K military Garwood PTO winches came with 9/16" HEX drain/fill plugs (six sided, not eight). You can swap them out with 1/2" female square plugs, I think I purchased my square plugs from mcmaster.com
I doubt it is original but you should be able to buy a socket to fit easy enough. Somewhere in the last 48 years somebody lost the plug and put this one in.
Actually, the plug is probably original. It is eight sided because it is a double square. Try your 1/2" ratchet or breaker bar. I am betting it will work.