A basic jimmy and the lock pops... a screw driver and yer in through the vent window... you can prolly bust the lock with a screwdriver and a hammer. Yes, I've known some shady people, tow truck drivers and a lock smith or two.
Leadfoot Lambert : from what I have read that one single pane sliding glass that sticks into the cab like yours is a OEM/Dealer installed dealie, but I don't have confirmation on that.
mbgmike's :
sliding glass window selection - click, then scroll down
-W