My mechanic is recommending a new voltage regulator for my bone stock 1975 280z. I installed a new battery a couple of weeks ago, and now my temp gauge is reading much hotter than it ever has, and the battery gauge indicates a slight overcharge, which the mechanic confirms. He suggests a solid-state voltage regulator. Opinions? If this is the way to go, does anyone know what Nissan part I should be asking for that will fit/work on my Z? Or, should I just get an NOS from Ebay? If that is best, is one brand better than another? There is a wide price differential, but I don't want to save money and get a bad part.

Thanks in advance for your advice.

The battery gauge wouldn't really indicate a slight overcharge. It's not very accurate. And the older external voltage regulators can put out up to 15.75 volts, which is high by today's normal range of 13.8 - 14.3 for an internally regulated alternator (pulled these from a rebuilt alt. install sheet). Do you have any numbers? Your mechanic may not be familiar with the older regulators.

The temp. gauge is also not very accurate and shares its voltage supply with the oil pressure gauge. The high number might just be an artifact.

Is your mechanic suggesting an internally regulated alternator with solid-sate regulator or an external solid-state regulator? You can still get the external regulators. Might be the easiest fix, if you do have a regulation problem.

But you need the voltage numbers first.

The mechanical regulators are adjustable. You should be able to lower the set voltage a bit.