I have same chasis, I liked the option of airbags and I installed a system that you can inflate or deflate the airbags on the fly, MARVELOUS!, even comes with a dual needle gauge!
On the steering box, Ive read on this forum that you can get away the (very) cheapy way out, is to alighn the wheels straight with the sterring wheel turned 90° to either side. the center "tooth" on the gear wears out and creates a "hole" that sure can be adjusted, but the rest of the gear will be very tight!.
Also DONT buy "remanufactured", wears again pretty quick... only NEW.