If the same as the 240, which I think it is:
Clean the area with spray cleaner, brush and cloth. Don't skip this step.
Remove the electrical connector. There is probably a "security wire" twisted around it in some fashion. This must be cut off first.
The sensor itself is held in with a ring about 1.5" - 1.75" in diameter. This ring is threaded on the inside. Just unscrew it and the sensor can be removed. I used a pair of channel locks to unscrew the one I removed. You have to balance the tension - enough to grip the ring, but not too much to force it oval. The sensor fits down inside a tube, and there will likely be a shim inside to set the distance inside the differential.

20 to 30 minutes

Dan