I made a tool out of a piece of aluminum with a long handle for my '68. I
believe the handle was about 2-3 ft long. You just have to make something
to fit into the ring and have enough length to give you the torque to turn
the flange. I had tried a large pipe wrench but you need more length. The
key is to have smooth even torque on as much surface of the ring as
possible. Hitting and hammering will not work.
Pete