I am new to this forum.Alot of good info.I just purchased an 08 3500 sierra trying to install nav radio.Installed the radio got the theftlock message.Took the truck to a Gmc and aChevy dealership to have the radio unlocked.Neither dealer knew how to unlock the radio.After paying $120.00 between the two of them I still don't have a working radio.Finally to my question does anyone in the Atlanta Ga area know a dealer that knows how to reprogram the new radios?Thanks for any info.