Old Mercedes Alternator: to Keep or Not to Keep?

How much $$ do they want for the rebuild?

I think partly right, yes it is nice to have all the original parts, but he also wants the money to rebuild the old one.
So how much does he want to do it??
Also is the car in good enough shape to warrant it?

So far he hasn’t said. I told him I would get back to him. The car is in pretty good shape having only 146k miles on it. It has the usual stuff with old cars, aging door gaskets and window rubber. I have all the parts to replace those. The major good thing about this car is it has nearly no rust at all on the frame or undercarriage. I have to say replacing the alternator was a titanic effort because of it’s location and weight. I pulled a groin muscle getting it in there. (ow!)

The rebuilt alternator is working?

Why not keep the old one “on hand” in its non-working state?

Yes, if the original is a Mercedes part numbered part, it would be of value. Replace the diodes and bearings etc.

I would hold on to the original. But it it can always be rebuilt in the future if you want to sell it or need it.

Wise advice. The parts to rebuild it later may not be available or may be more expensive. If you rebuild now, it will be available for your use at the moment you need it.

@Tropical_Willie is correct and original parts become particularly critical in the in the eyes of collectors.