Heres the #'s from the cowl tag of my 79.

79 1AW80 Z 307072
62D A52 61L 61U
06A--- 940203

Anybody know what the Z, 62D, 61L, 61U mean? I'm also confused as to the first # on the vin. Mine is a T, but all the threads I've read say it should be a 1 or a 5. The salvage permit says "GMC-El Camino"? There are cabarello stickers on the rear quarters but all other badges(steering wheel center) have the chevrolet sign. I have to pass a level 3 inspection to apply for a title so I need to know exactly what I have.

Here's some places I found with RPO codes

http://www.eonet.ne.jp/~barbarossa/rpo.html

http://www.c2e.info/rpocodes/MODERNGMRPO.html

http://christophe.salvaing.free.fr/rpo_codes.htm

all the ones you are asking about are colors. I can't help you on any of the others.
See what you can find at these pages

Good Luck