[Gromit]

Here's another one - inner fender to outer fender from a 1970 C10.

So far I think they are NLA unless you find old stock.

They (the U-Nuts) appear to me made from a single stamping; and it must have been a big press to flow the steel around in the die so much; unless they are stamped red hot but that sounds difficult too.

The only maker's mark is the diamond shaped logo.