How do you remove ignition key lock cylinder from 1993 Chevy Truck if you have the key?

i have removed the steering wheel on a 1994 Chevy truck with a 5.7 TBI 1500 series 4x4, it is requesting another pulley once the steering wheel has been removed and i need to find one of those. but i am not sure what they are called and if there are different sizes.