The latter construction (six-pin) was rather commonplace beginning in the 1890s (correct me if I am wrong) when Western Union and some other telegraph companies were doing widespread upgrading. Many CD 145 insulators were used for these improvements. "B" beehives seemed to be the rule here in the East for new insulators while Hemingray (H.G. Co.) insulators were used a lot more commonly during this period in midwestern US states and further westward. I believe but cannot document when exactly these lines were rebuilt. But it seems like any single-petticoat insulators (such as CD 133s, 126s, 127s, etc on the older, previous lines) (not being of Western Union "Standard") were not re-used and thus tossed by Western Union rebuilders.

When the forementioned iron-wire and 6-pin construction was upgraded to hard copper wire starting around 1910 (again at least here in the Northeast) the double-petticoat insulators were retained upon new poles along their routes, with ten-pin crossarm construction as the alleged "new" Western Union standard.

Also, at least here in the Northeast, Western Union installed lots of cedar poles as they upgraded from the 1910s. All of these had single-bolt crossarms with either 28 or 30-inch steel braces with wood-shank metal pins.

All of the above per my observations and findings...any further comments would be appreciated and will be shared as updates.

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