These billet aluminum cab mounts are a factory replacement for your 1963-66 Chevy C/10. The mounts are machined from T6061 aluminum and feature stainless steel hardware. The aluminum mount sits directly on top of the frame just as the original mount. One large stainless washer sits on top of the aluminum mount and will keep the body from digging into the aluminum. The large 1/4” thick washer goes onto the bolt and passed up through the frame bracket. There are no other lower parts to these mounts. PLEASE MAKE SURE THAT YOU USE PLENTY OF ANTISEEZE!! If you do not, the stainless bolt will seize on the nut and you will have to cut the bolt off! Please feel free to contact us with ANY questions or concerns.