Quick question quick answer.
 

Fast yes or no.
Does the 300 302 and 351 use the same alternator.

Yes & no. The alternator is usually the same within a given year, but the front case changes for some applications, and the rear case is rotated (clocked) for others. And there are a few versions of each alternator. So it depends what you mean by "the same", and what years you're talking about. In some years & on certain engines, you could install a 1G, 2G, 3G, or 4G with almost no modification to the mounting or wiring; other years & engines, some of those swaps would be more involved.

https://www.supermotors.net/getfile/...3gexploded.jpg . https://www.supermotors.net/getfile/...rnator2gex.jpg . https://www.supermotors.net/getfile/...ternator1g.jpg

Sorry I was in a hurry.
Saying take on from an 89 302 and drop it into my 90 300 for a week until I can get parts..
Edit couple hours later..
Lookin like it was just that the battery finally shat the bed, at a really random time.
Got another one on charge to see what happens.
Does the computer throw weird codes when the battery is super low like right now? I got 21 and 24 for the coolant temp sensor and iat out of range.
I figured I would check codes to see if anything pertaining to the charging system came up bad.
Thanks for the quick help steve.

If they are the same yes, but you could prolly make it work.

There is no predicting what an undervolt situation would do to a computer.

Adrianspeeder

Good news, it was the battery. The guy said take the alternator anyway. So I'm gunna snag it and some other quick parts and store em.
Didn't get to check the codes again, actually forgot. But there is no cel.