Bosch alt vs. Delco alt, 00-04 Monte Carlo
 

Buddy of mine is wanting me to replace his alt, while I was calling around today for price quotes they kept asking me if he had a Bosch or Delco. I didn't know and neither does he so 1) How can I find out and 2) Does it really make a difference? Let's say he's got a Bosch, could I put a Delco replacement in there and be fine?

I guess I thought Bosch made the AC Delco, but could be wrong. In any case, if he's not in too big a hurry, I have a new Bosch for the 3800 in my garage I only want $100 plus shipping for. Short story long, I heard a growling last winter I thought was the alt, bought this one off Craigslist (he claimed they list for $600 at the time), then figured out it was the idler making the noise (froze up and shredded belt). Traded the car for an 06SS two weeks later. Been too lazy to put it up for sale.

There should be a spec plate on the alternator that identifies the manufacturer, but the quickest way to tell is how the wiring connects:

Thank you sir. It's a Bosch....so anyone know if it's ok to use a Delco style alt in a Monte equipped from the factory with a Bosch style, and vice versa? Don't want to create more problems you know?

If it's not ok, why?

It looks to me like it would be a major PITA to swap them. The AC Delco only has 1 BAT wire and the Bosch has a BAT1 & BAT2 wire, plus the plug in connector is shaped differently so swapping them would require modifying the wiring. IMO it's not worth the hassle. Besides, the Bosch (125 amp) puts out 20 amps more than the AC Delco (105 amp). ;)

Can you elaborate on the BAT1 and BAT2 wire thing, not sure I follow you. I looked at both the Delco and Bosch alternators and they both have the same exact 4 pin plug...the only differences I see were physical, the Bosch alt was 125a like you said and the ground lug stuck out the side of the black shroud of the alt as did the 4pin connector

The Delco alt was 105a and it's ground lug and 4pin connector stuck out of the back of that shroud, pointing towards the drivers side of the engine bay. It also looked like the rear bolt housing (vertical, casted location on the alt case) was a tad longer on the Delco alt compared to the Bosch. Like 1/2" longer so you'd probably have to buy a longer bolt if you were to switch from a Bosch to Delco style alt.

I don't have both alternators here to physically look at. I'm going off what I can see in pictures of them online and in my repair manual. The pic of the Bosch shows terminals on the back marked BAT 1 & BAT 2 and shows a different shape plug. If the Bosch alternator you have only has 1 bat terminal and the plug shape is the same then it's possible the pics are incorrect. At this point I think I'd contact a dealership or reputable shop in your area and seek their opinion. If all the terminals have identical markings and located in the same position as well as the mounting holes I'd think that they could be interchanged, but I don't want to lead you astray. Sorry I couldn't be more help.

Thanks for your help....as far as I was able to find out, Chevy changed alts at some point during manufacturing, going to the Bosch setup which puts out more amperage. Aside from the physical differences I specified, they are interchangeable but if you have a Bosch alt currently you would need to get the longer alt bolt from the Delco alt. I can give the part# when I get home. If you're just replacing with a factory alt this swap wouldn't make sense due to decreased amp output but most h/o alt companies only offer the Delco style alts due to better performance and some other technical specifics.

That being said, since they hook up exactly the same way we're gonna go ahead and get him a Singer h/o alt.