if you are talking about the cylinder the key goes in to, then you need:
steering wheel puller (any GM one will work)
lock wheel compresser (AUTOXONE should give u these together for rent)
6-8" philips head screwdriver.
the ignition cylinder itself is held in by one screw on the right inside the steering column. just remove it, slide the key cylinder out and the new one in. line up the groves and you are good to go. ith ignition cylinder itself is like $10