I have a O.B. 172 and bought a new OB-F1-10S OB Fusion F1-10S 3/8x10 w/ OB Stitch Ring shaft to go along with my Fusion 6 shaft. I know O.B. went out of business and both my shafts have the stitch rings on them. Thank you for sharing about your 133 and your OB+ Classic with stich ring.