This is an F-body offset balancer that works with the stock F-body accessory drive and the six-rib serpentine belt. To install it, you need a longer bolt for your balancer puller. Use PN 1218 from Precision Performance Products. It is a 16x2mm-by-1⁄2x43⁄4-inch-long threaded adapter for the LS1. Whipple will supply the proper offset blower drive snout and lower pulley when you buy its blower. We used a 10-rib, 8-inch lower pulley.