Old rusted wiring connections

Just cut it off with maybe 1/2 sticking out and then get it apart and redo the terminals. They are called Packard (we used to call them Packard 56, but that may not be quite right. Look up some of Mattox posts he had a thread on these and where to get them. A couple of the places I bought mine are no longer, or have merged, changed name, etc
Just FYI it is Mattax not Mattox, but I found the posts. Very informative. Initially I was only looking for advice in removing the connector, so I could just plug the new harness in, not removing terminals. Now I'll look at removing the terminals and redo them like you mentioned doing. Thanks.