You might find a lot of philips screws in your GM truck have been rounded out or your screw driver slips while you are removing or tightening them. That is because they are not Philips they are Posidrive. It is easy to spot because of the little dots between the x on the screw (see photo) if you look at the two screw driver blades you will see at the part that enters the screw the Posi is rounded and the Philips is straight edged. The Posi drive will actually hold a Posi screw horizontal without being magnetic. Believe it or not I have taught a number of Snap-on and Mac dealers about this because they weren’t aware of it.