Allstar Performance Stock Style GM calipers are perfect replacements for most GM applications and will fit up to 1" wide rotor. Inlet thread is 7/16"-20. Right Hand (RH) Calipers or Left Hand (LH) designations are based on the caliper being mounted behind the rotor, as it is in most stock applications. All calipers may be mounted on the left or right. It depend if the caliper is being mounted on the front or back side of the rotor.