The design looks like some of the mid 70's hood side emblems but I haven't found one with That piece on the back though.
Definitely mid/late 70's, possibly from a C-65 series or from the "C" pillar of a pickup. My Dad was a truck mechanic at a GMC dealership in Cleveland all through those years & I remember seeing them on new trucks. A lot of what I learned about mechanics was from hanging around down there as a kid. God Bless & Merry Christmas Bill https://www.jalopyjournal.com/forum...ar-transport-hauling-open-or-enclosed.614419/
if you want to find out, use the internets to find pictures of trucks of various years, and look for yourself.
The Jalopy Journal
