I was just browsing through the technical info on Speedometers and thought I'd add this bit which many of you probably know.
The AC Speedo was used through 1969. It's the same speedo as the the 59-64 model. In 65 they changed the face to match the British tachometer. Then in 1968 they changed to the 150 MPH face to celebrate a Sportster going 150 mph at Bonneville.