Roundback vs. Squareback alternators?
I contacted the rebuilder who advertised a round back but delivered a square back and they td me the don't have round back cores. He said all the major rebuilders are in the same boat.
I disagree that the square back charge better at low RPM. Maybe they do maybe that don't.
I do know that the correct size pulley had more to do with idle charging.
My own testing showed that a 3.0" pulley charges for ****, square back or round at idle.
A 2.5 pulley on a square or round charges great at idle.
And I have posted video proof.