The only other thing I can think off is the transfer box output bearings. STC1130.
If they were worn i'd expect the play in them to be obvious and they'd probably cause the transfer box to weep oil through the output seals.
Sensors are available without the hub
If it's the sensor that's at fault, just replace the sensor.
Sometimes the problem is cause by worn bearings in the hub, in which case replace the hub and the sensor.
I tried an after market sensor on my TD5 once. It was an All Makes part and found that the sensor body was too long.
The toothed sensor wheel scuffed the end of the sensor and it didn't work for too long afterwards.
Binned it and replaced it with a genuine Wabco sensor and it's been fine since...
Got the tyres off the rims today and they're going to need some serious wire brush attention. Lots of oxidation bubbling up the paint on the bead seats.
It looks like the previous owner has tried to cure the leaking by filling two tyres up with some kind of goo and another two of them had the...