Jay,

Unless there is some burning reason to stick the old 10DN alternator on, a internally regulated one is the way to go. The 10SI is cheap and available in different outputs depending on how much stuff you have to power.

I have enclosed a link that shows a few different alternators, complete with numbers and typical applications. There is enough info to make a pretty good choice on what you need, plus some dope for the counterman which will allow him to find the part.

http://www.madelectrical.com/electricaltech/delcoremy.shtml

That site has lots of neat info, check it out. Good luck.

Stuart