Alternator - Internal vs external regulator

To my knowledge, alternators with internal regulators weren't available back then. If yours has one, it is not original which is hardly surprising for a 43 year old car.

Look on the front radiator apron drivers side next to the radiator, the VR is easy to overlook as it's tucked in that corner just to make sure you don't have one. I don't think IR came out until ~'80.
Jon

It's not easy to find since it's about as far from the alt. as you can get, seems like it should be on the pass. side in the same spot.

I stayed with the stock VR and upgraded to a mid '70's 100A alt. to handle driving lights, stereo, amp, AC, etc. I didn't want to have to worry about pulling too many amps. I'm also installing relays to take the load off of the headlight switch for the headlights & driving lights and give me better lighting than the stock 'yellow' headlights. The 100A is a little larger than the stock one but fits with all the same bolts/brackets. Some of the 1 wire don't charge until the engine gets rev'd past ~1500-2K rpm and just looks out of place to me, so you have many choices if you want to convert/upgrade.
Jon

There are arguments for and against either choice. Some people like to stick with the stock external because they are trying to keep their car stock, or because the regulator is often the part that stops working, so if its external then you can just replace the regulator, which is cheap. But if its internal then you have to replace the whole alternator...not so cheap.

Some people, like myself, prefer the internally regulated one wire units because it eliminates an accessory in the engine bay, allows you to go from 3 wires to 1, and is generally simpler and cleaner. I like that I was able to remove the regulator and the wires that run between it and the alternator, and have just the single wire going to my solenoid. For those electrical system novices, like me, it is one step towards simplifying the system.

I should mention that there are internally regulated alternators where the regulator is actually inside the alternator, and where a mini regulator is simply bolted to the back of the alternator. I have had bad experiences with the latter, so if you go that way make sure the regulator is actually "internal".

Powermaster and Tuff Stuff I have had great success with. And get at least a 100 amp. Its much easier than you think to overdraw a 60 amp alt. My car has died on the side of the highway more than once from doing just that.