The exciter ring is for the abs. It is a toothed wheel that goes on the third menber, and the sensor (the hole in the top) which is nothing more than a magnet counts the teeth and converts the pulses to mph. You dont need to do anything with it at all, leave the sensor unpluged and go for it. If you are changing gears, the exciter ring comes off easy if you want it gone. Pop out the carrier remove the ring gear and tap with a hammer. If changing to a locker or spool just toss the whole carrier. The rear covers are the same.