Due to a difference in rules across the board I opted to go with Engineered Diesels butterfly shutoff. Its pricey, but its also safety, where cost shouldnt matter. expect to have over $400 tied up when its all said and done. I wont say the price of the actual shutoff though. call chris or greg.
I havent decided where/how I will attach it out back but it will use PTO cable or similar(cable inside a cable) and terminate in a loop. Attached to that loop will be a zip tie.
If you go this route you must use a zip tie. When/if you come unhooked from the sled and the switch gets pulled the zip tie allows you to break away from the sled. Without it, the sled will rip your entire rigging system apart and everything else in its path.
I heard about one guy who ended up with a broken coolant overflow tank, an airbox ripped back against the cab and all kinds of other goodies.