Ok
The Dennis chip is clay.
It is not on the USPS records pre 1938.
That makes it a USPC 1939 to about 1949.
OR
A Burt chip pre 1948 as Burt went to injection mold in the late 1940's.
These are the only two companies (and years), that could have made the chip, IMO.

Actually there is a 3rd Co capable:
Anyone ever know of TRK making a C&S?
I could email Dennis if we are not sure.