8.1 vs. 5.3 alternator

[70c10guy]

Hey all, just a quick question. Have an opportunity to buy a used alternator off of craigslist. The part number is Remy 21108. It is listed for an 01 silverado for an 8.1... I have an 01 5.3 going into my truck and was wondering if I can use this alternator.. has the same mounting ears, and 4 pin connector... any differences for a 5.3 and an8.1 alternator? Thanks guys!

[davepl]

Can't say for sure, but if the physical mounting is the same and they're using the same connector, and they're from the same year application, I sure wouldn't have too many qualms about trying it.

When I look up 2001 Silverado 5.3, the numbers I get are Remy 21602 and 91653. Those are 5 3/8" and 5 3/4" cases, respectively.
When I look up 2001 Silverado 8.1, I get the same numbers.

The 21602 is 105A, the 91653 is 145A. Your 21108 is also the smaller 105A.

[dayj1]

Originally Posted by 70c10guy

Hey all, just a quick question. Have an opportunity to buy a used alternator off of craigslist. The part number is Remy 21108. It is listed for an 01 silverado for an 8.1... I have an 01 5.3 going into my truck and was wondering if I can use this alternator.. has the same mounting ears, and 4 pin connector... any differences for a 5.3 and an8.1 alternator? Thanks guys!

It'll bolt up and it'll work electrically. The biggest difference between the two is that the regulator plugs are in different locations. I've used the 21108 alternator on 3 swaps but I had the mounted down low in the f-body position and the plug pointed straight up. If you're using it on a stock 5.3 bracket, I can't say for sure that you'll be able to access the plug when everything is assembled. I don't know how much that helps, but it's something to look at. Good luck!

[70c10guy]

Went and bought the alternator, it's got a funky mounting ear on it that isn't used when the two holes are bolted up. You were right about the pllug in a different location. Still accessible though! Thanks for the responses!!