Replacing Steering Box On 435 JD

We had to replace the steering box on the 435 JD which was no problem, so I thought. I bought a used box and shaft from a tractor junk yard. It looked identical, shaft size, bolt holes and all. We cleaned it up, put it on the tractor, bolted up the rad shell and hood. Fired up the tractor to feel the new steering and got the surprise of my life. The gearing in the box was backwards. I didn't know it and evidently the guy at the yard didn't either, that JD used a right hand worm in some boxes and left hand in others. I'm just glad we weren't in close quarters. Needless to say, the whole thing had to come out, get another one, (double checking the gearing), ha,ha and do the job all over again. So, if you have to replace a steering box, make sure it turns in the right direction.