Both the 1966 and 1967 Shop Manuals are very misleading on this item, noting that the Hood Strap was only used on Intermediate Mercury Models. Yet, the 1967 Electrical Assembly Manual clearly shows that was used on Mustangs also (copy attached), as does the picture Royce attached, and the picture of mine attached here that I took during disassembly of my Engine Compartment.
These straps were part of the Radio Installation/ Suppression Kits that came for every Radio. Unfortunately, many times, not all of the components were installed. I have attached a picture of a typical Kit and its contents (the one attached is for a Full Size 1967 Ford).
These hood Straps were included in Radio Installation Kits back to at least 1957. Until the early 60's, they were Brass, making a good grounding material.
And yes, those are "points" on the top of the strap, and yes, they will scratch the underside of your hood - that of course is the intent in order to make a good ground.
Hope this helps.
Bob