To start with, My 99, Old Blue, didn't come with factory remote keyless entry. No code AUO on the door. I really really want a factory key fob though, so today I stopped by pick n pull and got this module from a 97 GMC Safari:
Tonight when I get home I'll pull the dash apart and see if by some small chance the wiring for it is already there. If not, I have the 99 factory service manuals from GM along with all the wiring diagrams. I should be able to wire it up. Then I need to order a key fob.
I did a search and can't see where anyone was as dumb as me and tried wiring a factory remote. I know it would be easier to just do an after market one but I'm kinda hard headed like that! Besides, everyone needs a project!