Steering box problems

[Smith & Sons]

On my 3rd ps box.last one from CPP was bad from the beginning,requiring constant adjustment.This one is from AGR,a variable ratio and it too required adjustment(3/4 turn at agr's direction!).It still has play so now they are telling me to adjust the thrust washer where the shaft goes into the box.I was under the impression that AGR was a quality outfit(price was higher)Has anyone found a quality supplier?(yes I did flush the lines,used new pump & synthetic fluid)