Alternator size

What you have is what is left of a 60 amp alternator.

The rpm ranges indicate a bench test after rebuilding, and would indicate a decent rebuild. Those speeds are alternator RPM, not engine rpm. Calculate alternator speed from engine idle speed & drive ratios. This is why underdrive pulleys suck - alternator performance falls off fast.

That old mopar alterator was a good design for it's day. It was designed to replace a 30 amp Generator, so the original versions were rated at 37 amps. Over the years they stretched that capacity to 65 amps or so.

When I say "what is left" I am speaking of the degraded performance from being rebuilt several times. Many rebuilt units come from high volume operations that part cores into bins and use anything that still works. If you put a 37 amp rotor in a 60 stator you get a 45 amp unit. Maybe. Looks like your rebuilder at least took the time to test his work.

When a stator is rebuilt, they put them in an oven and burn the insulation off of the wire so they can remove it. You lose about 6% of the magnetic quality of the laminations from doing this, because of the heat. If this is done more than once you can lose 18% or more of the capacity of the stator laminations. Your rebuilt stator with a good rotor managed to make 57 amps now.

That old mopar design is maxed out, rewound for almost double it's design amps. It was one of the very first units out there. If you want to run big power accessories with constant current draw like fans & audio you will need a more modern design in the 130 amp range. A 3G/4G hybrid will fit in the brackets, and make 130 amps minimum, and usually around 100 at idle. They can be hot rodded to 200 amps if you need it.

B.