A crimping head for use with an impact wrench to crimp fittings onto a structure carrying the fitting, that includes a universal adaptor having a head, and a socket positioned in the head sized and shaped to receive a standard anvil of an impact wrench without further connection between the impact wrench and the crimping head. A locking assembly is provided for cooperating with the universal adaptor head for locking the anvil into the socket, and a transmission is attached to the universal adaptor for being driven by the universal adaptor and for converting rotational movement of the anvil into selective rearward and forward movement. A jaw assembly is attached to the transmission and adapted to close into a crimping position and open into a release position responsive to the rearward and forward movement of the transmission.