This Lower Rear Coil Over Shock Mount Kit is great for the racer needing a custom set up that already has an upper shock mount. Designed for use with coil over shocks on a 3" diameter rear axle like most fabricated 9" and some factory 9" Rears, GM 10 and 12 bolt Rear Axles. Larger 1/2" grade 8 shock mount bracket hardware over the standard 3/8" that other kits use. Axle mounting brackets are laser cut for a 3" diameter axle.