Charging curcuit help

[Krosati]

Hi,
New to the group after checking around a bit. I hope someone here can help.

I recently purchased an 88 GMC Suburban and am having difficulty getting the charging system working. I replaced the alternator that was in the truck with the same type and replaced the battery. It still does not charge.

After purchasing a 5 book set of 1988 manuals, I am even more confused than ever.
1. What model truck is a 2wd sub? R or C?
2. The engine is a GM replacement 350 TBI. Would the RPO code still be L05?
3. According to the auto parts store, I should have a SI type alternator but the harness has the same long oval plug used on the CS121, CS130, and CS144 alternators. Was 88 a design change year or what?

Ok, since I have the wiring diagrams in front of me, I scan the C/K pages. Alternator plug is the same, fusebox is different, Instrument panel connector is different.
I now scan the G (van) pages, the alternator is the same, fuse box is similar, and the IP connector is different.
Now I check the R/V section and the alt is different but the fuse box and IP connectors are exactly as mine.
Which one should I use?

I've owned GM vehicles all my life and I never thought they could confuse me like this Burb is doing.