I replaced the plug yesterday. It was so rusted, I pushed a hole through it pretty easily. The "ring" of the plug remained firmly stuck in place so I used a Dremel cutter to remove the bottom of the cup and smooth out the edges.

I was afraid to try cutting the ring in case I couldn't get it all or left a rough surface that wouldn't allow the rubber plug to seal.

I'd post pictures but my phone doesn't want to download pics to my computer.

I took out the petcock as well and flushed out a little crud.

Next up is removing the leaking JB Weld on the crack and replacing it with MarineTex.

1950 Chevrolet 3100 (Ol' Roy)

1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)