Hello all,

I purchased an alternator for my 1979 SA and it looks like they may have sent me the wrong part?
Here is the listing: https://www.rockauto.com/en/moreinfo...192227&jsn=354

Main difference is that it is about 15% smaller than what is currently installed. The one I pulled out is by Mitsubishi. did I order the wrong part? Am i able to simply drill the mounting hole to be larger? What are my options?

Thanks in advance

Picture for reference:

 

u could just drill that hole out or thread it in from the other direction. pulley looks smaller, requiring a slightly shorter belt. make sure the plug connection is the same. i usually just have them rebuilt.

 

That is apparently a 35 amp unit. Your car came with a 50 amp alternator. I looked on RA website and the one your car requires is out of stock. Looks as if you purchased the wrong one. Rock Auto listings are frequently incorrect. 1st clue something's amiss is that it won't readily bolt on in place of the other and as you mentioned it's smaller than original.
If this were an emergency and you were trying to get car home,it might be worth making alternator fit somehow. Installing an alternator that's 15 amps less powerful than what car came with will cause undercharging and low battery issues.
Think your best option is to return that alternator to RA and source correct one elsewhere. I saw correct one on Autozone website and Advance Auto.To get the correct one,be sure to tell them it's a 50 amp model,without an internal voltage regulator. Both places had them in stock and they're about twice what you paid for the one you have now.

 

Do you still have an automotive electrical shop in your area? They are kind of a dying breed, but you very possibly could just have your existing alternator rebuilt. It used to be the normal way to fix your alt's and starters. Today less people work on their own stuff, plus we have this disposable mentality. Might be worth a try to do a search and support a local business.