Diameter, diameter, diameter, alternator pulleys

First video, newly rebuilt square back alternator with 3.75 dia pulley.
https://photos.app.goo.gl/t6jbzbnnfiT3EB2p8
Second video newly rebuilt round back with 2.5 dia pulley
https://photos.app.goo.gl/Cpjcr3SzWekvi5Qq6

Same single field wire regulator.

Both alternators setup for single wire field.