For removing the lower BJ, with the weight of the truck supported on a jack stand, and w/ the susp. at full droop, remove the large nut, and knock the BJ loose, the lower A-arm should then fall away far enough to remove the BJ from it. If there isn't enough room, you may have to loosen the shock(or remove the upper nuts completely), or using a bottle jack and a small 2x4(between the jack and a 2 wheel studs) lift the upper A-arm up a little to give you enough room.

As mentioned the serviceable BJ's will last longer than the non-serviceable ones. A lot of the aftermarket BJ's have a bolt where the zirk fitting goes, you can just replace the bolt w/a fitting and have serviceable joint.