Power Steering Leak, Rebuild or Replace

[STPL]

I have a very slow leak coming from the bottom of my steering box (pitman arm seal?), the power steering still works fine but I would like to stop the leak. I don't know wether I want to drop the 100-150$ on a new steering box that I can just swap in, or if i can get away with replacing the seals myself. Will I be able to replace that lower seal without taking the pump off the truck? Are these steering boxes normally rebuilt or replaced? Please see link for pictures.

http://imgur.com/a/HAL1C

 

[IIBRONCOS]

Usually they are rebuilt, although you may save a lot of time by buying a rebuilt unit, instead of doing it yourself.