Muncie Transmission Assemblers

[TangoBravo]

The Muncie transmissions have a number of unique stamp identifiers on the top rectangular boss at the rear of the top of the maincase. I have an understanding this is possibly an assemblers/inspectors stamp when originally put together?? Has anyone compiled a list of the different ones? I have seen a square with diagonal line and a diamond. I think there are many others as well. Is this stamp attributable to a single assembler/inspector?
There also seems to be a single letter stamped near the countershaft hole on the case fronts-any ideas on these?

[69z28rsbilly]

I had a 1969 M22 that had a heart stamp .....

[Jon Mello]

Here are a few I have.

[TangoBravo]

I suspect there could be a large variety of these. Has anything been established on its purpose?

[Jon Mello]

Not to my knowledge but I assume they are an inspector's stamp.

[bcmiller]

Inspection stamp. Lots of different ones were used. And not always in the same location.

They don't really mean anything other than the unit was inspected before sent out the door of the transmission assembly plant.