Should be a T-40 Torx bit.
T55 TORX BIT ON THE FRONT 12MM SOCKET ON THE REAR!
It uses a T45 Torx bit.
Removing the Key Switch requires a special torx bit screwdriver with a hole in it, or you can use a basic torx bit and use a drill with a small bit to drill out the center part of the screw with the stub in it that wont allow a normal torx bit to go into.
You will need a T55 Torx bit to remove the front caliper of a 2001 Silverado 1500. A torx bit is a screw with a six point star shaped head. These come in different sizes.
Torx is a 50 and they are really tight.
Actually it is not a Torx bit -- it is a hex. I believe it is the largest one usually included with Hex sets.
T - 55 TORX, Across the board for similar GM's.
T-40 bit!
A T60 or T65.
It is a T55
The correct size Torx bit is a T-55.