Looking for cabin filter on 2008-9 silverado

Cabin filters can be located in two different places on your vehicle IF they exist. My 95 Cadillac DeVille does not have one. SO either you can access it from behind the glove box, meaning you have to unscrew the glove box and remove it to see the access port to change it, or 2) lift the engine hood and look on the passenger side by the firewall at the bottom of the windshield. There may be a box access port there. IF those two locations does not have a place to change it, then you don't have one.