What do you need to know, Mickey? I've done several TR3As, shouldn't be any different for a 4A except you won't need to convert to negative ground.
In fact I just picked up an alternator today to put in TS13571L. Didn't get quite the same model shown here
but it's similar.
As I've done before, I'll probably replace the lower mounts with a single long bolt & some suitable spacers (making sure one of the alternator legs can float on it's sleeve). The bracket with the slot for adjustment can be bent to fit. And I'll just bore an original pulley (if necessary) to fit on the alternator shaft, so I can continue to use a wide belt.
This is a "4 wire" alternator, I'm not sure offhand what the 4th wire is for. I'll join the big output terminal together with the brown/white and brown/blue wires at the original control box location. The 'sense' input gets a new wire to the starter solenoid; and the 'lamp' output connects to the small brown/yellow wire that was on the 'D' terminal of the control box (which runs to the warning light on the dash).
The 4th terminal <span style="font-weight: bold">may</span> be supposed to get ignition voltage, in which case I'll run a wire to the fuse block. Got the information around here somewhere, just not handy at the moment.