Thanks for sharing your discovery
Easy to see that you found a Metuchen example do you have any information on the car so that it can be labeled correctly for documenting. Didn't already have one from 69
Some examples from 68 and 70 NJ Mustangs
Most plants had a method to identify the inspectors and documenting who checked sub assembles or processes. Methods often included, numbers or names depending on production period. They also needed a tool (stamp, sticker...) or method for fill in personnel that would fill an inspector for vacation or sick purposes. Since Ford claimed that one out of every ten employees was an inspectors there were allot of them. Have been told that often the fill in man was often someone that use to fill that position (promoted) so that standards could be maintained.