easy to remove, rebuilding is a little more difficult. easier to just replace it, i've heard of some upgrades from the junk yard to. like getting a dodge durango gear box. anywho, you will need a good pitman arm puller to put your pitman arm on the new box.
edit: although, if it is just a shaft seal, that could be replaced to save money. but you can also run into worn parts making the seal go bad.....eh...just replace it.