Kw T660 axle temp gauge

[Poppa chop]

Have an 09 t660. Looking to add axle temp sensors. Was told the truck is wired
and all I will need to do is daisy chain on the dash with the other gauges.
I do know I’ll have to add sensor to differential. Where would the wiring be located that I’ll need to start this process. Any input would be greatly appreciated.