An ultrasonic clamp coagulator system that is configured to permit selective cutting, coagulation and clamping of tissue during surgical procedures. An elongated portion of the instrument can be configured for endoscopic applications and has an outside diameter of less than 6 mm. The system includes a one-piece torque wrench that is provided with cantilever arms aligned in an annular fashion about the centerline of the torque wrench. The cantilever arms include teeth in an inward perpendicular fashion in relation to cantilever arms. The clamp coagulator includes an outer tube retainer that includes spline gears projecting in a perpendicular fashion along the outer circumference of retainer. Torque is transmitted through the cantilever arms to the spline gears for attaching a handpiece to the clamp coagulator.