front brakes pulsate and abs activates

Hey everyone--

have a little bit of a problem, i think i know what is wrong but i want yalls opinion. I have a 1998 z71 4x4 pickup, when i press the brake pedal i get a little bit of a pulsation and when the truck is decelerating with the brake dpressed the abs activates at 10 mph down to zero sometimes. I have replaced the rotors and pads with new ones and rotated the tires with no change. i know that the abs system works with a magnetic sensor in the hub so i am suspecting the hub is going bad. anyway has anyone had and solved this issue?\

also if it is the hub, are there any specail tools to take the hub off? i have never done a hub before.

thanks in advance

DB

also what is the size of the axle/hub nut?

also, if i am backing up and i tap the brakes i get a light clunk from somewhere in the left side suspension and if i turn the steering wheel to the right and hit the brakes while backing the clunk gets louder.. any ideas?