I'm not making a recommendation, just taking info from 220/226 book. Page 270-05-6 "A slow return @ stop valve is located in hydraulic cylinder head. It controls the rate of oil flow returning from the hydraulic cylinder to reservoir and by turning the knob in clockwise completely until it gets stopping, hydraulic cylinder can be shut off from the hydraulic system.
By turning the knob in anticlockwise, the valve starts opening and allows faster oil returning flow to make the faster lowering of lift arm.
The stop valve may be used to hold the lift arms in an up position by setting the lift arms to the position then turning the stop valve in. The oil in the hydraulic cylinder is trapped between the piston and stop valve. This trapped oil holds the lift arms in position."
I just completed installation of a 3 point cement mixer on my 2002d. This mixer has a single acting cylinder that pivots the mixer up and down. On the left side (sitting on seat left) of the stop valve body there is a removable plug that allows you to operate a remote single acting cylinder. I installed a quick disconnect at that point. I now raise the mixer to desired height, close stop valve and three point handle then operates single acting cylinder. I didn't just come up with this idea, it is in the same manual.