Mud is what kills mine. I have used Timkin bearings as well. The water and mud gets inside the the bearings and over time eats away at them. I also tried to press the beaings out of the hub, thinking I could cut costs by buying just the bearings. I took 8,000psi before the whole assembly exploded. The bearing race is actually made into the hub. I do agree with doing it yourself though. It's easy, and you'll save about $200.

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2003 Ranger FX4 level II. 3" BL, 33x12.50 GT Radial Mud Claws, Custom front and rear bumpers with winch hookups, custom flatbed, with hi-lift, and full size spare mount, 12,000 lb winch mounted under bed, Electric fan, and of course a flowmaster.