[dubie]

that rubber is the seal for the grease. They come included with a new shackle kit. You can jack up your axle to relieve the strain, remove the carriage bolt and nut, remove the shackles and then replace your seals. Put it all back together in reverse order and grease it up. If you need to remove the pin, it just threads in and out and the bushings are driven out pretty easily with a deep socket or piece of pipe and a hammer