The speedometer are electronic yes there is an electrical wire connection from the transfer case to the instrument cluster. The sensor at the transfer case reads the revolution from a small plastic speedo gear.I have a 06 TJ. I believe my speedo is electronic?
The megashort and supper short SYE do not use that little plastic gear. The sensor reads the revolution right from the output shaft that is why you cannot simply calibrate them the normal way via changing the speedo gear.