Stringing block threading apparatus for use in uncoupling a junction in a conductor hauling line and inserting a threading loop therein previously assembled through the throat of a stringing block. The hauling line is advanced along power line towers by a helicopter and the advance sections of this line are separably joined by a double ended coupling. This coupling is deposited into the threading apparatus atop each tower where it is automatically disconnected from the hauling line allowing enlargements on the released section ends to separate and become trapped in respective mating couplings at the opposite ends of the threading loop and the leading one of which is of the same double ended construction as the one deposited in the threading apparatus by helicopter. This coupling is deposited in the next threading apparatus for a repeat threading operation.
