Mostly CD 104s and 121s here with the exception of a CD 102.4 that sits on the upper crossarm, second out from the center. My opinion is that the much larger "groove" area beneath the upper wire groove on this style was intended to wrap twisted pair "cord" subscriber drops from. Immediately beneath is an "attempt" to do this but an ordinary single-groove (a CD 104) insulator resides on the drop-wire pin. Early subscriber wire was individually twisted rubber-covered copper wire and cloth covered.
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