According to my 1940-53 Motor Magazine repair manual, the 49-50 Pontiac ran a 30 amp 6 volt generator, Delco part #1102711. The corresponding regulator is a Delco #1118301. A 49-50 Chevrolet generator, same amp capacity, is an 1102710, and the manual lists the same regulator as the Pontiac.
Olds and Cadillac run a 40 amp generator, with a different regulator part number.
Jerry