I found this in a box of ignition related parts in my garage...but I don't know what it is...I own a 78Z but I don't recognize this as a part from that year model Z...unless it's mounted way up under the dash (or some other "hidden" location.  Any help is most appreciated.

 

OK...since I first posted this question, I've been scouring the internet for the answer to my question. I'm thinking that it is a voltage regulator but I still haven't figured out which year model Z's used this part. To the best of my knowledge, the 78Z didn't use a voltage regulator like this (alternator was internally regulated, correct?). Thanks in advance if you could provide me with any other information on this.

I think that you are correct.  A PO from the past might have had more than one Z.  They went to the internal regulator in 1978 as you thought.

That looks like one of the solid state aftermarket units.  

It is a voltage regulator. The plug style was used 75-78 and possibly late 260. Early 260 had a one time only round solid black plug, all 240’s had a 6 pin rectangular flat pinned plug. 

The parts fiche gives you an idea of how many unique ones were made and start and stop dates.

All do exactly the same thing. You could switch plugs and use a reg from any year technically.

At some point in the late 280’s the alternators went to the internally regulated style (designations starting with LR rather than the earlier LT) and the external regulator nonsense was put to rest.

Many replacement regulators you buy today have transistor based relays rather than mechanical ones for enhanced reliability if you are stuck with an LT alternator.

Common practice now is to use later GM or later Nissan alternators with higher output anyway. Tons of threads here and else suggest what you might use. 

 

Edited February 16, 20232 yr by zKars

Thanks to you both for that insight. Your comments were very helpful!