SPC Performance Steel Upper Adjustable Control Arm & Caster Rod 64.5-66 Ford Mustang (Pair)Update '64. 5 to '66 Ford and Mercury front suspensions by installing this pair of adjustable upper control arms from SPC. Each arm has a built in +3. 00 of caster to improve return to center with modern radial tires. The camber curve has also been optimized by utilizing the 'Shelby Drop' geometry in the billet aluminum cross shaft. Arm pivots are maintenance free xAxis Sealed Flex Joints for tight, responsive handling. Camber can be set to 2. 00, 1.