Looking in the manual, the 60 and 100 use the same mounting bracket. Only difference between the aluminum and steel that I can see has to do with either using a through bolt for the alternator pivot, or using 2 separate bolts front and rear.
The 196900 split has to do with the serpentine belt system. Above that uses an extra pulley between the alternator and PS pump. Below that doesn't. Also different PS pump designs. These are A2 and newer trucks only, so all have the 200 amp alternator (unless they have the 400 amp)
I don't believe the 100 amp works with the 200 amp bracket, because the 60 and 200 use different brackets.
100 amp was only on A0/A1 trucks, so V-belt systems, not serpentine.
So I guess there is no reason to keep it as a backup for the 200A.
It came off the DuraVee, a 1993 M998 with low miles, I thought it was a 200A by the pictures, as it turned out someone just dumped it in position when they pulled whatever alt was in there.
I did pull the regulator and tested it on my 200A, it was toast, I need to make a run into CC anyway so I will stick a good regulator on it and have my buds down at the ye ol starter/gen shop give it a spin.
When I bought GEP turbo engine for the Detroit I could have had the 200A alt and the starter for $500 more, hindsight says I am a dummy
I wonder if Neihoff has a troubleshooting guide for it, I suspect the 200A guide can be used, for the most part they identical electrically but for size/capacity
I would expect the field windings to have a little higher resistance.
