Wow, you're blowing my mind with the insulators you're finding. That is a 136.4 "Canadian Boston", nice early threaded Canadian insulator. If any of these are for sale or trade, I'm interested, send me a PM or email me. The Montreal telegraph, GNW, and Great Northwestern are the main styles I collect.
Hi 143 Tallboy : I am interested in selling most of the insulators , but I am assuming you would need more detailed pictures and if the price is reasonable, I will consider the sale.