Okay.. I got a couple used boxes from a friend.. put one in, and guess what!!! STILL EFFED UP... it WAS better but still very bad.. my old box had a lot of play, this used one (from a '79 blazer with stock tires/lift) is much much more sensitive and luckily it doesnt leak a drop. Also I noticed that when I had my old box off, I could NOT turn the input shaft by hand, but with both of the used boxes, I easily could.. that also lead me to beleive that there WAS a problem with the box. Well back to the parts store to get a new pump.. good thing I was doing that too, because that "good as new, rebuilt" pump literally died while I was getting the new one.. in neutral at 3-4K rpm it had ZERO assist.. I actually hurt my wrist, trying so hard to steer the beast.i had to make a stupid looking 6 or 7 point turn just to back out of the parking lot at napa..
well this brings me to my next point, dont buy a cheapy rebuilt!! go to a quality parts house like Napa for one.. the first 2 were from autozone and they were JUNK. I should have learned my lesson years ago about that, but mark my word I will never buy another rebuilt part from them.. new/brandname is all they are good for, IMO.
as for rebuild kits, i priced 'em and they are about $40 but it was a special order kit and I didnt have time to wait.. I still havent looked inside the steering box, so I really cant say how hard/easy it is but I have a feeling its not just a walk in the park.. My advice is get a good used one.. i think junkyards guarantee their used parts anyways so you really cant go wrong..
if you have any more questions feel free to ask
thanks and good luck