For those of you who may be interested (and to update this post with correct information), I spoke with a Prestolite representative today. While I do not understand all of the acquisitions and sales that occurred many years ago, Prestolite possesses archival information on the Autolite generators. He confirmed from the archival information that the difference in the letters at the end of the part number denoted different pulleys. Specifically, the ODs and IDs of the pulleys on the A and B versions differed enough that I do not believe the A version will work on a 1941 Plymouth Special Deluxe P-12 (which the specs indicate requires the B version).