someotherguy
Truly Awesome
That decodes to a 1999 C3500 (C meaning 2WD), 5.7 engine. The 1GB prefix is built in USA, Chevrolet division, "incomplete vehicle" meaning a chassis cab truck that came from the factory without a bed installed, so that an aftermarket upfitter might install any number of various work beds. It came from the Flint, MI plant.
Coming with a 5.7 that's probably what it still has, because if one were to go bad, by far the easiest to source/install would be another 5.7. If you post a pic of the engine it should be easy to identify. It may even still be the original as the Vortec 5.7 can go several hundred thousand miles if not outright abused.
The catch with yours being a 1999 is that's 2nd year for them to have the Passlock antitheft system. As you can see it's not stopping you from starting it with a screwdriver.. because there's a resistor module set in the tumbler that is "read" when you turn the tumbler over (with key, or screwdriver, or frozen small dead animal paw, etc.) vs. some of the older systems you may have seen with the "chip" visible on the key itself. For you to retain functionality of the system (ex. start the truck when you need it to) you'll need a tumbler/key set meant for a 1998-1999 GMT400 model. The resistor in the new tumbler will need to be learned into the system once you install it, or the engine will simply start then immediately stall each time you crank it, as the antitheft system will kick in.
You can have the tumblers in your door locks re-keyed easily by any locksmith to match the key for your new ignition tumbler.
Richard
Coming with a 5.7 that's probably what it still has, because if one were to go bad, by far the easiest to source/install would be another 5.7. If you post a pic of the engine it should be easy to identify. It may even still be the original as the Vortec 5.7 can go several hundred thousand miles if not outright abused.
The catch with yours being a 1999 is that's 2nd year for them to have the Passlock antitheft system. As you can see it's not stopping you from starting it with a screwdriver.. because there's a resistor module set in the tumbler that is "read" when you turn the tumbler over (with key, or screwdriver, or frozen small dead animal paw, etc.) vs. some of the older systems you may have seen with the "chip" visible on the key itself. For you to retain functionality of the system (ex. start the truck when you need it to) you'll need a tumbler/key set meant for a 1998-1999 GMT400 model. The resistor in the new tumbler will need to be learned into the system once you install it, or the engine will simply start then immediately stall each time you crank it, as the antitheft system will kick in.
You can have the tumblers in your door locks re-keyed easily by any locksmith to match the key for your new ignition tumbler.
Richard
