Hi All!
I have a 2000 GMC Sierra 2500 New Body Style with a 6.0 liter engine. I bought it used several years ago.
The Delphi alternator is going bad (loud bearings). I know which alternator belongs in the truck, but I am really confused about which alternator is the existing one.

The RPO code is KG8, indicating a 130 amp alternator. I think I may have a 105 in the truck.

But, when I did some part shopping & research on line, I saw that the 130 amp version has two differences from what I pulled out of the truck:
A) There is a large separator between the case halves on the 130 and no separation on the 105 amp. (Photos of mine are attached below.)
B) The 4-pin plug on the 130 is at 12 o'clock and the plug on the 105 is at 11:30 o'clock. (Mine's at 11:30)
- This stuff is from on-line, so I can't guarantee it's accurate or current.

Another curiosity is that there are steel spacers between the mounting plate and the alternator body (where the bolts go through). This look like it is designed so two different width alternator bodies can go on the same bracket, or someone did a modification to put a smaller alternator in.)

ID On The Existing Unit:
On the body is the number: 10480386W 105 R 120 N (The N might be something different. The numbers are light & look hand punched with pin punches.)

In local auto parts stores, the alternators are all quite different than either of the ones described above, so I could not figure it out from there.

Why This Confusion Is Stopping Progress:
If I get the 130 and the existing one is 105, I understand that I'll have to change the serpentine belt. That belt was just changed a few months ago (but I didn't do the job, so I don't know if it's the belt for the 105 or the 130.)

Do any of you know, from the photos, if I have the 105 or 130 amp version?
And is it true that if I do have the 105 and get a 130, I'll have to replace the new belt?

Thanks For Your Help. I sure appreciate it

Paul

 

In case anyone stumbles on this, here are two ways to tell if you have the 105 or 140 amp alternator:

The 105 amp and the 140 amp have one very distinct difference. If you look where the two halves of the casing meet, the 105 amp halves are quite close together. The spacer is less than 1/8" thick. On the 140 amp, the spacer is quite a bit thicker- perhaps 1/4" or more.

Another way to tell is to look at the serpentine belt's part number (stamped on the belt). If you do an internet search for someone selling the belt, the seller's description will say if it's for 105 or 140 amp alternator.

In my case someone must have switched from 140 to 105 because the RPO code was for 140, but the alternator (and belt) were for 105.

I hope this information helps someone someday!

 

In all the alternators I've replaced on GM trucks, I have never needed to distinguish between output or belt. I simply go to my GM dealer and get the correct parts .... otherwise, if it's going on my own truck, I take my old one in for its core return and visually compare the two.

But I've never experienced a difference in serpentine belts. I just get whatever belt or alternator the parts catalog calls for.