Joe,
The fact that it's in such a late box ('70s style) and still has the same p/n proves it's not Chevy car or light truck, or Vette, as it's not in my books. BY that I mean that number would be in my books. Looking at some other similar numbers, I now believe it could be back to '55 vintage. If it's not BOP I"d have to believe it's BIG truck.
Is that p/n on the box or just molded into the part?
Verne