The Patent Numbers were probably no longer valid when that latch was made. Chevrolet more than likely outsourced the latch because it was still in demand into the 1970's. I remember buying a new in the box 1957 Chevy car rear bumper ends back in the late 70's, they both came in new GM boxes with all the right part numbers, but looked like they were stamped with a press that was half as strong as it needed to be as they were covered in wrinkles. So with that all said I think you have a GM authorized latch that was made way after production stopped. If it fits and works, I'd use it as it's going to be way better than the repo's that are made now.
Mike B
