FOR THE CREW CAB: After making numerous calls to dealers, I finally found information on the SPEAKER wiring diagram for the Colorado Crew Cab . They are as follows:
Front LEFT Door: Tan (+); Gray (-)
Front RIGHT Door: Light Green (+); Dark Green (-)
Back Doors: Brown (+); Yellow (-)
Apparently, in some models, the RIGHT REAR door has blue wires. If this is the case, here is the polarity: Dark Blue (+); Light Blue (-)
Just thought I'd share this so it's now available in one place.
Information compliments of Team Chevrolet at Northpoint (Atlanta) (free plug).
Crew Cab, Z71, 2WD, Silver Birch, Dark Pewter Cloth, XM .. looking to install new speakers soon.
If you can't live in Colorado, then at least drive one!