You referred to "
the small bracket that mounts to the bellhousing...". Both big block and small blocks received a bracket that holds the starter wire harness away from the exhaust which attached to the bellhousing via the top right-side bolt. As the wiring harness was installed at Fisher Body, the clamp would likely not have been bolted to the bellhousing until after the body drop at the Chevrolet (VN / NOR) Plant. The bellhousing bolt that attaches the clip and harness received engine paint (overspray) when the block was painted with the bellhousing attached. From reference photos of original cars I believe the bellhousing bolt was removed following body drop for the bracket / starter harness to be attached, therefore the bolt should also have tool marks (paint damage). The clip is natural steel with the clamping end vulcanized rubber coated. Below are photos of the small & big block clips (they are different). Also a photo of a 9,600 mile 69 Camaro SS L78 with the clip attached.
Original Small Block Clip with Starter Harness attached.
Small Block Clip (top) vs Big Block
9,600mile 1969 Camaro SS L78 survivor with it's untouched clip and bolt.
Note: paint and tool marks on bolt.
