To clarify:
5000s (1947) + 6000s + 1-50s: Three point cineston controller. 5000s originally had a 4th point but this was disabled when the 6000s showed up to make sure they'd play nicely with eachother. Photo:
http://www.flickr.com/photos/davidfulla ... 2991134579
2000s: "Fat" cineston-esque rotary controller, four points of power and four points of brake. Photo:
http://www.flickr.com/photos/davidfulla ... 7570765497
2200s + 2400s + 2600s: "Joystick" controller, four point of power and four points of brake.
3200s: Cineston-esque rotary controller, four points of power and four points of brake.
5000s (2009): "Joystick" controller, no notches. Basically a big potentiometer.