For the record it was the sensor on the diff. The AC output was nil so I got the replacement and checked the resistance vs the original and it was way out of wack. Pulling it out was a bit of a pain-- it snapped off where the steel sleeve ends. Then the guts came out w/o the steel sleeve. Used an angled drill bit powered by pliers to finally pull the sleeve.
New one went in, buttoned everything up. Check engine cleared on startup, ABS by the end of the driveway.

Thanks to all that replied.