Click onto "View Original" and you will see faint stenciling on the lower crossarm (on its left) that has New Eng. Tel & Tel Co. lettering. The insulators surely look like CD 104s. The crossarms were held in place via lag screws and not through-bolts. This was common practice for New Eng. Tel. & Tel. Co. from the 1880s through around 1910. After that time 10-pin crossarms were typically used with through-bolts affixing the company's arms to their poles.