1997 Lumina Rear wheel ABS Sensor

I need to replace one of my rear wheel ABS sensors. I guess it's built into the rear wheel hub assembly. I have taken off the rear wheel drum and removed the four bolts to the hub assembly, but the hub will not come off. Is there anything else I should be doing? Do I need some type of puller on it? TIA

Has no one ever replaced a rear hub on one of these cars?

It's been a while. And not on one that new.

http://www.autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/0e/de/36/0900823d800ede36.jsp

take a look at this...

Thanks for the reply. I seen that and thought it mounted flush. I finally got it off. There is a round portion sticking out from the rear that fits thru the backing plate. It was a somewhat tight fit and after rusting in place took a few hard hits with a hammer to loosen it enough to slid out. Next up Cam Position Sensor.