The Bolt-On Rear 4 Link System for 1973-1987 square body c-10 replaces the leaf springs to provide excellent ride quality, handling, traction and load capacity. It is completely bolt-on and provides mounting for Shockwaves or CoilOvers. The panhard is adjustable so you can optimize your tire clearance at the new lowered height and the mount has been located to optimize the bar length and angle for the lowered height. This helps keep the rearend centered in the truck and lowers the roll center to mimize body roll. The R-Joint rod ends combine the best qualities of low friction movement, lateral stability, full range articulation, and quiet operation into one special bearing that is as home on the street as it is on the racetrack! The C-notches are included with the kit and FIT the frame rail.