Easiest internal regulator alternator swap for dual belt FE

[BigBlueIron]

I might be late to offer another senerio but I have had extremely good luck with these, https://store.alternatorparts.com/7078-conversion-regulator-for-1g-alternators.aspx

Nice to be able to keep stock everything while being able to ditch the extra wiring, fits flush of the rear bearing so it doesn't not inhibit fit. Also there is a rheostat built into the back to adjust voltage output if desired but Ive never needed to adjust one. Of course you are still limited by max alt output but in my opinion it makes the old 1g work better then ever. And it seems I have plenty of the old 1g's laying around for replacement but really they rarely fail.

[Falcon67]

I don't use the SI-10 type GM units because - at least on the SBF and 351C - the case interferes with the cylinder head.  They are longer than the Ford units. 

[TomP]

There was a GM alternator on my 61 Meteor when I bought it... quickly got rid of that! It was mounted in typical GM style too, about a ten degree angle off  from the belt. Also like a GM it did the 2000rpm dance, quite spectacular how far the thing could move and not throw the belt.

 The GM also uses a 3/8" bolt on the lower through hole, so either drill it larger or you can't use the 7/16" threaded hole in the block.
 Not sure why those are so popular, I guess like all tilt columns being 70's GM style...monkey see monkey do.

[Falcon67]

The 3G units use a 10mm bolt on the lower ear - you can keep a 10mm wrench handy, or drill/tap it out to 3/8-16 easy enough.

[babybolt]

Those 3G alternators never seem to wear out.

Back 10-20 years ago there was a foreign alternator that was being used.  Maybe Nissen?  It looked fairly close to the early 60-70's Autolite alternator only smaller.  Anyone remember what exactly these were?

[Falcon67]

I run a small Nippondenso clone on my dragster.  About 50A.  There is a kit to bump that somewhere on the web.