Washington Water Power Co had a thing for using gray glazes during the 1906-1915 era and all the 60kV transmission lines they built used gray glazed insulators during this time . Early on (1906-07) they used Victor M-4325's with blue-gray glazes . Later (1910-1915 )they used M-4321's and by Ohio Brass and Victor as well as the M-4321c with a gray glaze . Of all of these the rarest seem to be the M-4321 with the VICTOR/ R=00 insulator logo marking. Robin Harison found a few of these back in 1997 with the large logo stamp in a sub station on the electrified Milwaukee road but none with the small marking . I found two broken ones with damaged tops with the small logo in Idaho that I was able to repair as well but nothing whole .
FINALLY after looking for a good one for 20+ years I found a whole one this last weekend in near perfect mint condition. It had been languishing unmolested on a wooded mountain side for at least 70 years . I have been able to date the production of this piece to the year 1913 based on the history of the line it was installed on . With the exception of the M-2430, I have seen very few gray glazed VICTOR insulators with the large or small Logo stamp so this makes this find pretty special !