I need to replace the alternator on my '72 Supreme and was able to source a 63 amp version. The one on the car now is a Delco Remy but how would I know if it's original? I ask because if it is, I don't want to use it for a core for my new one.

 

What is the part # I will call my buddy up @ gm to ck. I bet if you post the # somebody on this sight will also know..

 

Where would I find the part #?

 

should be right on the top of the case around the top side where you would tighten the bolt after adjusting the belt.

 

Original ALT part number should be stamped into the casing resembling image below...
Lots of threads/posts on this site demonstrating ALT part number locations & date codes...Search is your friend here.





Alternator Date Code

 

I didn't see any numbers on the casing when I took it off, so I'm guessing it's not the original.

 

Pretty sure any Delco unit would have a part number stamped into it. They are also fairly easy to rebuild, especially if it was recently working and not sitting in the elements for a decade.

Do auto parts stores still bench test alternators for customers?

 

Yup, but I have no idea what the part number would be, so there's no way to bench test it without the correct parameters.

 

Yes

 

I did see "10-3" stamped on the back of the casing.

 

A local rebuilder vs. a big box auto store is a much better option if that is an option for you. They'll often take your core even when upgrading to a different model.We have an old school one in town that is excellent, he personally tests and rebuilds the components.