1970 Mustang Mach 1 Cobra Jet 4 speed built in New Jersey on 10 Sep 69
Found on underside of hood with yellow stamp markings and Trunk Lid drivers side also with yellow stamp markings.
I think the underneath side of the hood is "Paint OK"
"Paint OK" is also a generic term used to describe the paint and other inspector stamps or stickers used at all plants to identify a required check was completed. Different plants, production periods and in some cases individual inspectors had their own method though most fall into identified patterns. The numbers or name used identified the inspector for accountability purposes. There is a short description of these markings in the article on Basic Paint Markings in the Library section of this site
In the case of inspecting the paint job, like other plants, usually one inspector was assigned to the line so they inspected the unibody with specific parts attached while another inspector was assigned to the individual body parts being painted on a parallel line. For this year and plant the unibody inspector applied his stamp to somewhere on the trunk lid - each inspector had his favorite/typical location sometimes depending on body type. While the individual parts like fenders and hood on this year were stamped by the other inspector. One particular inspector, maybe more, liked to stamp multiple times on the same panel for some reason
The basic pattern and method you have found was used at NJ for many years.
Here are some early 70 NJ hood and trunk lid markings
But not really sure what the side of the trunk lid marking states.
See above
Has anyone seen these stamp marks on other cars.
Hundreds