I have seen them but why would you want to put all that mess on every pieve of equipment you own.
THere are some better quick hitches out there. THere is one that you just put the regual pins in all the spots for the 3-point on your equip. Then the quick hitch comes from the bottom and latches around the pins.
Then if you don't want to use the quick hitch, the pins are already there and you hook it up to the tractor like normal.
I will look around for a link, or some one else might have one.