I have a 1970 Cutlass Supreme Convertible with 350 2bbl. I'd like to upgrade to a HO alternator but there seem to be so many different kinds. Can anyone tell me if I should use "one wire capable" and whether or not I need internal or external regulator? I'd like to use the same setup I have now just with higher output. Was thinking that would be the easiest swap with no additional wiring needed. Suggestions?

 

Is yours now internal or external regulator?

 

I'm not sure what a "HO" alternator is, but if you are upgrading output, the first question is why? Unless you have added many electrical options (electric fans, electric fuel pump, obnoxious stereo), there's no benefit to upgrading alternator output.

In any case, DO NOT get a one-wire alternator. I'll let you exercise the search function on this site for reasons why. The easiest upgrade is to simply get a 12SI for a 1980s-vintage Custom Cruiser with Olds 307. Those have 78 amps, which will be more than adequate unless you've gone crazy. Rebuilt units are under $70 (including the core charge) from RockAuto. Wiring is shown below.