Another update, this related to AMC models in the early to mid 60s with Motorola charging systems.
As stated above, the first models/years to use the Motorola alternator used the 3 wire transistorized regulator with the "TVR" designation (simple enough - Transistorized Voltage Regulator")
TVR12AM18 is a good example and is shown below. This is a transistorized voltage regulator, 12 volt for American Motors, model 18 of the series. These used an external resistor to provide field excitation.
- A very early AMC/Rambler electronic voltage regulator by Motorola ->
This post discusses the "retrofit" or replacement of the TVR series with the newer (newer back then) regulator model R2-1. This model incorporated an internal resistor which negated the need for the external resistor and extra wiring.
The R2-1 looked much more like its successors, the R2AM1 and R2AM2 models.
This is an example of the R2-1 regulator as used by "Rambler" to replace the TVR regulator - Note the same 3 bullet connector, but the addition of 2 yellow wires -
This is the bulletin these newfangled regulators came with -
The wiring is very simple, and you can see they are paving the way for the use of the R2AM1 regulator in size, mounting, etc.
So the early AMCs went from using the TVR series, to the replacement for the TVR, the R2-1, then moving on to the R2AM1, and that was later replaced for 67/68 use by the R2AM2 (which again was much like the R2AM1 it replaced, but with black tag and different voltage setting)
Then in 1969 and 1970, the R2AM4 with the different connector.
In the spring of 1969 Motorola announced it was moving to a new model numbering scheme, dropping the OEM designators from the model numbering system in favor of a more uniform (and cheaper to stock) universal system - meaning the alternators then later the regulators would no longer have "AM" in the model number.