ABS light
It sounds like you are correct about the speed sensorbeing the source of your trouble. It should not be too hard to find someone who could pull codes, which will tell you for sure which wheel.
If you force me to GUESS I would guess the rear sensor, which should still be mounted on the to of the diff on a 2000. It is easy to change and there is no gap to play with.
The ABS module sends the wheel speed signal to all modules on the communication buss, so if one or more speed sensors signals are bad, weak or erratic you get the light and loose cruise. If the sensor is the rear, all ABS is gone, if it is the front you still have Dynamic rear proportioning, which is electronic proprotioning valve.