Here's CP's standard lower-voltage distribution insulator from the 1930s or so. The cement joint is no longer the "Goddard" type as in [id=473701838;M-2312A], and the crown and lower shell have been trimmed down a lot more so it doesn't resemble [id=473703910;Sim-M2312A], either.
This example is unmarked, but examples with P-inside-C, C.P.Co., and differently-sized "C.P." marks exist. All are ink-stamped.
This glaze is typical of the 1930s to 1940s era of CP production.