I have a slight leak in the front seal of the steering gearbox. In the process of investigation I decided that rather than just replace the seal, I'd like to replace the box with a fast ratio remanufactured one. Looks like the best price is Cardone.

I've never worked on steering before. How involved is it? Are there other parts that I should replace in the process (like the rag joint)? And, do I need to fully drain/purge the fluid, or can I just pop in the new box and top up the fluid? The parts are original except the hoses, I think. But, everything under the hood was out and rebuilt just over 2 years ago (by the previous owner).

Thanks.