There are two kinds of voltage regulators for stovebolt trucks- - - -"Delco-Remy" and "Wrong!" Ebay usually has a good variety of used 6V GM regulators, and a few new ones if your budget can take the hit. Don't necessarily limit your search to Chevy- - - -Pontiac, Buick, Olds and Cadillac will probably work, as long as the item is 6V Negative ground. 6V GMC regulators will be Positive ground, and might not work as well as one with the right ground polarity.
Just checked- - - -there are at least 25 "new old stock" Delco-Remy 6V regulators on Ebay today, plus a large number of used ones. It would be hard to GIVE me any brand of regulator other than Delco for a GM product, based on 60+ years of making a living in the automotive trade.
Jerry
