The 67 GT350s have an alternator wiring harness (C7ZB-14305-E) specific to 289s with a tach.
There is a different part number for 390s, so let's stick with GT350s for now.
My alternator harness has been with the car for over 30 years and has a stator wire repair, which leads me to believe it may be original rather than replaced. The boots are Ford style (although the colors are degraded) and no repairs are done anywhere else. I believe the correct boot colors to be FLD (white), STA (black) and BAT (red). Due to age these morph into all kinds of weird colors.
However, the issue I have is with the battery connector end that SA connects to the standalone terminal stud near the solenoid for the ammeter.
All of the reproductions have a square plastic end molded around the large eyelet. Two of the standard Mustang non-tach alternator harnesses I have are also square.
My "original" harness has a rounded plastic molded end (see pic -- right).
Either my harness is incorrect or there may be more than one vendor supplying these.
I'm about to have mine reproduced with what I think is its correct round plastic end but would appreciate some input.