Here is the spec page from the 1973 Dodge FSM. Shows a 50 and a 60 amp with HD or A/C. Don’t ask me what the car line letter designates. I found it in this manual once when I was working on my Dart (but have forgotten) but I looked through both volumes and a supplement tonight and couldn’t find anything but the VIN designation. Can anyone elaborate on why Dodge had service manual letter designations different from the VIN letter? The damn manual has instructions on how to bend it to line up the black tabs! Why wouldn’t the different car line letters be spelled out big and bold on the first freaking page???