Find that the number in that area (along with the one often found on the top center area) likely identified the worker or assembled or completed one of the processes used in assembling or setting the third member up originally. Have seen at least four different colors used for that marking depending on year and time. Not unusual (we see it allot) for workers to "make their mark" so that if there is a problem the boss's know who was responsible
I'd like to confirm Jeff's suspicion. In the blue collar world it can be common to have a bonehead working in the area. I've seen guys slyly mark their output to CYA in case the boneheads stuff comes back. Not saying that this is the case here. But I would suggest to keep this in the back of your mind if you see uncommon marks. I entered the manufacturing world in 1973, non automotive. It got to the point that the company assigned us little stamps consisting of animals, symbols & geometric doodles to mark our stuff with if we so choose to do it. They kept a record of who had which stamp. So by at least 1976 there was enough demand for shop floor personalised marking that some company produced these stamps.
I can only imagine some mechanic pondering over what in the world these little childish stamps meant on the parts he was repairing. Some parts crossed a lot of operations thus a lot of stamps.
Long time lurker, first post. Thanks for reading. Not of a lot of people left now that were on the shop floors back then. Just giving a little insight into what it was like back then.
