Bad power steering after box

1997 K2500 6.5td 4wd, 130k miles

I just replaced the steering box & pitman on advice from the
alignment shop that the original box was screwed in and couldn't be
tightened any more.

Now it acts like it either has air in the system or worse. There's from zero
to ok power assist when not moving, appears to improve when I rev the
engine, but its intermittently jerky. I tried lock-to-lock both wheels up
and on the road. I had originally tried to bleed it by removing the hp line
from the booster area, but it spurted violently, yuck. With the belt off, the pulley turns easily and smoothly, no noise other than a gurgle when reverse direction. Did I kill the booster, the pump or the belt? The steering fluid came from 2 containers since
I was working on another car recently. I may try to empty and replace
with new fluid.

Also, if I pull hard on the wheel, it slips/ratchets as if the splines on
the steering box are bad. The steering column did slide on the first attempt, which amazed me because they are keyed, so I don't understand
how the splines can get hurt. I double checked and gave the pinch bolt
an extra tightening.

Going out for another test ride. See if it works better warmed up.

It's important to check the preload - I replaced the box on my Ford E350, and it was WAY too tight. If you have a Hydroboost system, it needs to be bled; a quick check is to see how the brakes are - spongy or too much stroke, there's air. Typically, the Hydroboost is the high point in the system.