They had punched out the door lock on mine too, they also took the top part of the steering column off and the black piece that your key fits into, looks like they stuck a screwdriver or something into the ignition but failed to start the truck.
see this is where the PASSlock system in the GMT-800's actually does its job. If you get some stupid punk idiot who tries to shove a screwdriver into the ignition, hot wire it, or take apart the steering column/ignition switch, it will disturb/ruin the PASSLock hall-effect sensor and therefore not send the ECM a challenge/response fuel-enable data signal...
The GMT-900's actually use a "chip" (passive transponder) in the key which is much harder to bypass. To steal a GMT-900 you'd not only need a properly-cut key, but you would also need a Tech 2 to re-learn the transponder/chip in the new key. Even when doing a force-key-relearn with a Tech 2 the ECM
still makes you wait 30 seconds before it will allow the truck to start, as an additional deterrent to stop a professional thief who actually carries a tech 2 with him.
GMT-800, all you need is a properly cut key and the truck wont know the difference...it will pass anti-theft, start up normally and drive away.
GMT-900's, as I explained above, are much harder to steal. Id be willing to bet if a pro wanted a GMT-900 he would just bring a tow truck, because even with thousands of dollars of Tech 2, correctly cut keys, etc you still need to wait 30 seconds before the ECM will accept the new/relearned key....which is longer than most thieves will want to stick around...
Ben