No disconnect wires at gen, excite the field and test voltage for no more than a few seconds at 1500 or so, rpms report back with what you have for volts. ****og voltmeter is better than digital for this test, imo
That particular car uses the generator armature terminal to ground the starter relay for the "gas pedal start". You may want to start at the starter relay and verify that the armature terminal is not grounded or wire is fried.
On a 56, I believe it is mounted on the left front inside fender well. It is not much bigger than a horn relay, but has 4 terminals.