The correct alternator harness entirely depends upon whether you have an ammeter or the alternator indicator lamp (and not really the presence of a tach or not). In almost all cases, the presence of an ammeter dictates a three pin connector to the alternator harness and three pins used at the voltage regulator.
If you have an alternator indicator lamp, then the system uses 4 pins at the alternator harness plug and 4 pins at the voltage regulator.
Cougars are different than Mustangs (which may explain my confusion earlier, as I am more familiar with the lower animal form…) in that many versions have tachometers and ammeters. For Mustangs, that didn’t happen until 1971. All Mustang catalogs call out wiring as to whether you have a tach or not, which is absolutely incorrect: it is the presence of an ammeter or idiot light. That is also true of Cougars.
The plug for a car with an ammeter has four wires but only a three prong connector. See my post with photo of both the alternator harness and the engine bay harness connector.
Fair enough. When I say 3 pins, I am referring to the number of plug sockets, not the number of wires going into the back side of the molded connector.
You keep saying four pins when in fact there are only three. I am very careful to say wires when I mean wires and sockets or pins when referring to those.
Pretty sure the Mustang engine compartment harness is the same with regard to the alternator plug I just don’t have one here to look at. I have three '68 XR-7’s and four XR-7 harnesses here. All of them are identical.
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Fair enough. When I say 3 pins, I am referring to the number of plug sockets, not the number of wires going into the back side of the molded connector.
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Royce is correct regarding Mustang and Cougar 67/68 alternator plugs. I spent a fair amount of time researching, and the four pin alternator plugs first appear in 1969 (at least for Mustangs). The 3 pin plugs likely have different wire colors for each year for the alternator indicator lamp/ammeter versions. There is a fourth wire on some versions where a line goes directly from the B post on the alternator to the starter solenoid, bypassing the 3 pin connector.
My statements above regarding the number of pins used on the voltage regulator still hold up (for the alternator indicator lamp and ammeter).
I humbly apologize (once again) for confusing the Cougar community.