Spark Advance, Street Fire, Mechanical Advance Kit, Weights / Springs, Gm / Street Fire HEI Distributors, KitThese MSD advance kits are the same kits that come with your MSD distributor. The kits include the needed components to make your distributor perform like it did when it was brand new. Advance Weights Included: Yes Advance Limit Bushings Included: Yes Spring Quantity: 6 Adjustable Vacuum Advance Included: No Quantity: Sold as a kit. Notes: Designed for GM style H. E. I. distributors. Will not work with computer controlled HEI.