Fareastdriver:
USN, Kaman SH-2F Sea Sprite (for that matter, A-E and G as well) had that feature which allowed for exceptionally fine tunning of the rotor disk. You could, using two switches in the overhead panel, adjust the cones, (A/C and B/D) as well as asjusting the track (using A and B) motors. I don't think any other helicopter I've ever flown could be tracked to such a fine degree, in terms of how smooth the ride is. (A well tracked CH-53E, with seven blades, produces nearly as smooth of a ride).
I flew SH-2F's back in the 80's. There are plusses and minuses to that design feature.
One plus is that you can fly the bird with zero hydraulics.