[Piston]

Those seals can be a PITA. First chore is getting the pitman arm off (use a pitman arm puller). Remove the snap ring and both seals... easier said than done. I remove the snap ring then start the engine, turn the wheel HARD to one side while a buddy watches for the gush of fluid. I'll warn you though, if the P/S isnt working or that seal is leaking badly enough that trick will not work and you wind up digging the seal out with a slide hammer or seal puller. When that happens, I use a small body dent puller and a drywall screw to screw into the seal then hammer it out.
Be VERY careful putting the seals back in, the first one is the pressure seal and will leak if everything is not done right.

Might be easier to find a used one or buy a reman unit. Keep in mind you still have a no assist issue! (which wont be dramaticly affected by the leaking seal unless its low)

EDIT This info is for changing the seals.