GT4 RS. Left.GT4. Lower cntrl arm bolt. Right.GT4. SPYDER RS. A fastener used to secure a Control Arm. A threaded rod with a drive head (such as hex, 12 point, torx, etc) on one end used to secure the Differential Housing to it's Mounting point. Part cannot be reused/reinstalled. Rack and Pinion Bolt. Suspension Crossmember Bolt.