igntition switch repalcement?

[C15_Sierra]

Are you talking about replacing the key/lock cylinder or the ignition switch itself (located behind the dash on the column)

I've only done the ignition switch and not the key, and I've never done it with the column on the truck, but replacing the ignition switch assembly is really easy - unhook the connectors, unbolt two screws and the assembly comes right out. May be a tight fit if your hands are too big (mine are relatively small). The ignition switches are different for tilt wheel vs. non-tilt (the rod travel is reversed).