[CompClassics]

As Jeff & DAN stated above it was very similar to the leaf spring to upright fastener except that the leaf spring bolt was hollow to allow for a grease fitting and lubrication. There was a flat machined onto the bolt head and a corresponding tab was on the suspension pick up point to trap the bolt from rotating in the bore of the pick up point. If the bolt was allowed to rotate a groove would start to wear into the shank of the bolt causing a weak area that could fail.

Jeff,
The race part was fabricated from military grade hardware with similar modifications to fit into the suspension pick up points.