What size alternator?!?
 

Ok I'm trying to figure out what size my alternator is. But there is one problem, it only has two words on the thing. It says Delphi Automotive on it and that's IT. Is there a marking on it some where that i don't see that tells me what size it is or what? I have not a FIRGGIN' clue.:argh::argh::argh: Could some on tell me how to identify this subject? It would be great.
Thanks
Lucas

what is the alt off of? make model year would help alot.....

I think some part stores can test how much your alternator is putting out, not sure if they can tell you how big it is. I know someone that works at a Dephi plant, I'll ask him tomorrow.

they don't have the ability to load test alternators.... an alternator and starter rebuilder shop should be able to look at it and tell you. if it is for the 99 GMC then it could be a 105A or a 130A. the only way to tell is the diameter of the case. 105 will be 135mm or 5 3/8 inch in diameter and the 130 will be 145 or 5 3/4 inch in diameter.

if not for this vehicle please let us know what it is and i'll see what i can find.....

I'll get out and measure it this afternoon after i wake up.
Year model is 1999 new body style serria 1500 2wd 5.3

Call Autozone. It should not be very hard to find this alternator. Theres probably millions of these trucks on the road.

I think it's the 130A b/c it measured close to 5 3/4. But if it were such a big alternator it should be able to run at idle at nigh with out the lights dimming correct?

regulator is prolly flaking out on you.... what is the voltage at the battery while idling and at ~3KRPM's with the headlights on

Also make sure all of the connections are clean - especially the grounds.