A top drive power swivel assembly for well drilling rigs having a travelling frame for moving along a drilling tower. The travelling frame has at least two lower and two upper travelling frame extensions. A housing has at least two upper and two lower housing extensions each with an opening. A first connector penetrates openings of upper travelling frame extensions and openings of an upper housing extensions engaging the travelling frame to the housing. A second connector penetrates openings of lower travelling frame extensions and openings of lower housing extensions to securely engage the travelling frame to the housing. A top drive power swivel mounts to the housing and the top drive power swivel receives power from hydraulic motors. Various sheave assemblies mounted to the travelling frame engage a hoisting means. Guide wheel assemblies disposed on the travelling frame engage the tubulars.