ok, problem solved.
My nephew was kind enough to drive 70 miles and bring his laptop, computer diagnostic program, Alldatadiy subscription and the alternator from his own '03 Suburban.
We didn't connect his alternator right away but rather went through the troubeshooting process.
We were immediately stumped when he attached the OBD2 connector but the program didn't recognize a vehicle attached.
After searching the web, he found a post that said to check the cigarette lighter fuse because they're on the same circuit. Sure enough, my fuse was blown. We replaced it and thankfully the program noticed the vehicle.
When the analysis was done, it showed codes P1637 and U1041. The U1041 is the ubiquitous ABS/Brake warning light. I'll clean that ground later.

In the end, P1637 error code troubleshooting chart lead us to a bad alternator.
We installed his alternator to verify and sure enough, it worked.

So after a week of cussing, scraping knuckles and puncturing skin...it's what we originally thought...the alternator. What led me astray were the, not one but two positive bench tests at O'Reilly's of the alternator and battery. If I had purchased an alternator and it didn't fix the problem, O'Reilly's wouldn't have taken it back so that's why I didn't do that earlier.

I actually upgraded to a 145amp for an addtional $10.

Anyway, thanks for everyone's help.

 

This is why I don't like posting help to questions. If you don't want to take the advice don't post "I don't think it's that, or no can't be that". Glad you got it fixed, hope your nephew can take your next problem, cause I won't.

 

kevinkpk,
I tried all that you suggested and appreciate the help. My not knowing exactly how the PCM interacts with the charging system didn't give me a definite feeling that it was the alternator. As I said, it checked good twice and if I had purchased a new one, I wouldn't have been able to return it.
Anyway, thanks for the help but I won't look for anymore from you.

 

I posted twice to check the alternator, you never posted back.

 

I too suspected the alternator, but having it "pass" at the auto parts store for sure gives misleading info... Glad you got it going..
What program was your nephew using on his laptop?

 

He used "Auto Tap". He had it loaded onto his laptop running WinXP. Pretty sweet little program.