Thanks all for your input- and yep, I was talking about the NUT one size DOWN from the one lying under the pitman arm!! 8^]
Got the nut off with a 1 5/16" socket (had to go up to 3/4" drive, never had those before!), then couldn't get the blasted pitman arm off. 40 yrs sure makes for its own form of epoxy!! Ran to the local Auto Zone, picked up a pitman arm puller, and voila!! My '66 now has a new front end!
Now, if I could just find a damn tool to shut the rain off for 2 days STRAIGHT so that I could get an alignment!!! (on the East Coast, I think it's rained non-stop since St. Patrick's Day.)
Thanks to all who contributed to this topic- this site rocks.