Excellent (and large) photos that should help others. Didn't look too corroded, at least to those guys in the east, but aluminum is very unforgiving. I once had a Chrysler alternator that wasn't charging, and ditto for the replacement. I then thought to run jumpers from case to BATT- and it then worked. It was just bad grounding of the aluminum case. Another time I had the cluster on my 300D pulled out and saw smoke coming from the speedometer cable as I cranked the starter - corrosion in ground strap to alum case of tranny and it was using the speedo cable as the current return path.

Interesting spur-gear tension adjustment on that 1978 alternator. My 300D's have a finicky bolt & nut tensioner that likes to destroy itself. All that seems a bit over-kill. On my old Chrysler cars, you just tighten a nut while you simply pull up on the alternator. You don't want the belt too tight anyway (wears the bearing).