PTO Adaptor - Female Spline 1 3/8'' - 6 X Male Spline 1 3/8'' - 21 with Clamp Bolt. - Sparex Part S.15904PTO Adaptor Female spline 1 3 8'' 6 x Male spline 1 3 8'' 21 with Clamp Bolt. S. 15904 This heavy duty PTO adaptor is designed for applications exceeding 70HP. It features a 1 3 8" female spline with 6 splines and a 1 3 8" male spline with 21 splines. The adaptor is 165mm (6 1 2") long and increases the length by 121mm (4 3 4"). Product Specifications Alternative to: 3742 Brand: Spenco Connection Type: Clamp Bolt Duty: Heavy Female spline (ins): 1 3 8