[grivera]

When I acquired my 69 Lemans, it had after market gauges that had their own harness. Not sure what became of the factory temperature wire. Also, the car has a regulator on the firewall. There were three wires to the alternator - two small and the large power wire . The two small ones weren’t in a connector. Is one of them the temperature sensor wire? Is this the correct type of alternator?

[gtohurstjudge]

Those are the original Alternator wires, but the plastic plug that the two small wires
plug into is missing because that is a later model alternator that takes a different style plastic plug. That is commonly done because the parts store didn't stock the correct style 69 model alternator. The temp sender wire
is located in the bundle of wires that travel down the left valve cover. It is a small gauge wire and is green in color. If you unwrap the tape on the harness next to the left valve cover you will
most likely find the remains of the green wire that has had it's end nipped off.

[gtohurstjudge]

Regarding the alternator it is a later model version because in 69 the two small exciter
wires plug into the back of the case , not the top of the case. That looks like a mid 70's style alternator.

[grivera]

Great - thank you - will this style alternator work ok with an external regulator? Also, re: the alternator wires, does it matter which wire goes on which prong?

[gtohurstjudge]

Yes it does matter......you cannot reverse them. It looks like your alternator
is the internal regulator style of alternator that was introduced on Pontiacs in 1973, but
I can't say for 100 percent sure. If your car doesn't have an external voltage regulator on the firewall and the system is charging, then it has an internal regulator style of alternator. You cannot run an internal regulator alternator with an external regulator.

[grivera]

It does have an external regulator on firewall- I acquired the car last July and everything was connected this way - including the external regulator on firewall. The alternator is a power master -if no part number on it is there anything to look for to determine if it’s internal or external?

[gtohurstjudge]

I believe there was a short period where the alternators were externally regulated but had the connector on top and not in the rear. that must be what you have.

[johnta1]

The external regulator alternator has prongs that look like ||, while an internal reg. alternator has prongs that look like — —
(on the alternator where plug attaches to)