Why would you want to do that. Neither of my ZTR mowers have that feature and I am glad they dont. I sure wouldn't want the clutch kickin in and out all the time while at max throttle.
I have a Craftsman ZTS 6000 and a Ferris IS700 and the mower runs till you push the PTO knob down. The engine will die if you even shift in the seat with the PTO engaged. They wont start without the parking brake locked, the levers pushed out and PTO disengaged. That is plenty of safety for anyone. I don't think they make an interlock for zero turns that stop the blade when in reverse. If they did, they would be stopping every time you made a turn as you back up on one lever and push forward on the other to turn sharply. I think you are confusing them with the tractor type that stop when you put it in reverse but I think most have an over-ride switch for that and most people just disconnect them anyway.
I think that "safety" feature was the stupidest idea on the planet anyway.
