The category covers hex and flange bolts, body and panel screws, shoulder and stud bolts, and the bolt-and-washer assemblies used on suspension, body and engine brackets. Many listings are the exact fastener called out in a factory parts diagram, which is often the only way to get the right length, thread pitch and flange diameter together.
Around 4,000 fasteners are listed, divided between bolts, screws and studs, in the GM, Ford, Mopar and ACDelco numbers that appear on the original. Thread sizes range from small body screws up to the larger suspension bolts, and the fractional sizes appear in the title — a 7/16-14 bolt is a different part from an M12 even when the heads look alike.
Three numbers decide fit: thread diameter, thread pitch and length under the head. A fourth decides whether the joint survives: the grade or property class, which sets the torque the bolt will take. Do not substitute a hardware-store bolt for a suspension or driveline fastener — if the original is marked, match the marking, and if it is not marked, match the factory part number.
