Squareback vs round back alternator?

Wayne, Don't you have a thread going about this on your car? I ask because its very confusing in this thread, and it might be clearer if it was its own thread.
Your post follows a discussion with Christian about a very early A-body with a slant six in Germany, which in turn followed a discussion about operation and performance....

Yes as mentioned in the 'sticky' revised squarebacks are physically larger than previous squareback or roundback.
https://www.forabodiesonly.com/mopar/threads/identifying-chrysler-alternators-1960-1976.475691/
Some other threads we've discussed various pulley issues including that some of the common replacement pulleys are not quite the same as originals. Aftermarket stuff can be a pain these days.

1975 has some unique power circuit wiring and differs from '74 and '76.