I have a 735 with the splined PTO and over the past 20 years, I've replaced the coupling twice and last year I visited Joel at Earthtools and got another coupler and engaging fork, I also got the 3" PTO extension and attached it to the tiller. The extension has the female splined end that stays engaged to the tiller and on the other end that attaches to the tractor has a new male sllines that the coupler engages. Joel said that was the easiest and cheapest route to solve the worn splines on the tiller that was causing it to wear the coupler and start jumping out of gear.