many important advantages as compared to prior known welding guns the square rod portion 38 b of the electrode adapter can be slidably received in the square opening in the guide block 40 to preclude unwanted rotation of the electrode adapter the design allows the ready interchange of the power cylinder 34 with a servo motor such as for example the servo motor 100 shown in fig3 the use of the identical side plates 20 to establish all of the critical dimensions of the components of the gun can insure that tolerances will be maintained on all of the critical dimensions and at all of the critical points the use of the identical side plates 20 further can simplify reconfiguration of the gun since the shape and configuration of the side plates can be changed to accommodate a different welding requirement while continuing to use much of the same components of the welding gun in the new configuration the rod portion 38 b of the adapter 38 can be chrome treated to enhance work characteristics and reject weld splatter the use of insulating plates 82 to embrace the electrode holder 46 can allow a metal to metal configuration at the arm engagement and the holder to prevent rotation of the arm under usage the design can allow dual attachment points of the electrode adapter or shunt adapter to allow for a new attachment.