The Original Boat Levelers on my 1965 21 still work fine.
Tricky part is drilling the 1/2" hole at a 45 degree to run hydraulic hose through the transom. They use a soft low pressure hose instead of a hard wall high pressure hose like the Bennetts. Only fitting is at the pump and at the actuator nipple. Only complaint I've heard is the clamp at the actuator is unimpressive (it's nylon), but but hey, they work.
