yeap, those alts with the stator barelly visible between half cases are wider not just on diameter but also on deepth. No matter if 60 or 78 amps, but simply being the 80s alts. I have never tried to fit a later stator on an earlier case actually or if this would make difference on the full size. Sure will look some weird with the ridge around.

Rotor is "the same" at least on size. The difference is really the stator. My alt went bad and once I used an older square back alt rotor I had laying around and worked the same. I couldn't notice any physical difference between my old squareback rotor and the one on the 80s alt.

Diode packs... not phisical diff either. Dunno on ouput capacity, but sure not phisical diff

I made that alt upgrade on my car and, as mentioned on some magazine article ( upgrading the charging system on a 67 or 68 Barracuda ) and for a nice fit some other changes are recomended. On my car what I did is trim around 2 or 3 mms the rear alt spacer to keep the belt aligment.

I also used a longer belt, because the rear of alt met with block, so need to pull away a bit more the alternator from the block, for BB at least. At the end came out perfect. Sure having RV2 compressor the longer distance ( which is already long from factory ) will make slap a little bit more the belts when AC is on, but the diff is no HUGE. I got the belt to set the alt away just enough from the block and get the propper aligment allong with the rear alt spacer.

I think this wouldn't happen on pre 68 setups.... not at least on the belt lenght, but would need the rear spacer trim

Yes, Most of upgraded alternators are based on this later setup, I.E., Powermaster, Dbelectric. HOWEVER Tuff Stuff are using the earlier square back alt per I have being able to check on cars already using those, so if you don't want to deal with the rear spacer trim or longer belt, this could be the way to go. I'd go with them when money is enough for that.