Update on this supject!
Recently a good friend brought a box of parts and told me to enjoy, wow!
You see, my friends Dad worked for the railroad where new cars came in.
He would find odds & ends along the rail tracks and pick them up.
Among the items in the box were 4 original battery clamps.
They were all painted (dipped) a semi-gloss black. The
clamp seemed like it was phosphated prior to paint and I did find a new stamping.
Before, the only clamp stampings I had found or heard about were 'K' stampings.
But one of the four had a 'C'.
The phosphate coated clamp under the paint.
The 'C' Stamping!