brother, you've got the right idea re getting the setup checked by a competent shop, and if you're having trouble figuring out the stock setup, an alternator won't be any easier - a Delco 10 or 12 is the standard GM alternator used on most things, from early to current, but your main problem [aside from how to hook it up] will be the mount and adjuster arm, they weren't on anything as early as the 235 .... if the shop can't get the generator setup going, they might have some advice for an alternator setup, and you might find some helpful info at
Mad ElectricBill