So, night before last, I pulled the steering box off. On the bench, it was so tight that I could barely turn it with a socket and breaker bar on the shaft. That's when I decided that since my daughter would be driving the rig, I didn't want to take any chances with the steering. I hit the O'Reilly's by my house yesterday morning. Turns out that the manager there has a '99 TJ and he had never heard of the Durango swap. He was so intrigued by it that he sold me a Durango box for the TJ price ($30.00 less) and even matched Advance Auto's 20% on-line discount. He didn't care what I brought in for a core, so long as it was "a chunk of metal that looks like a steering box". While I was at it, I exchanged and replaced the rebuilt pump that had been growling since I put it in three weeks ago (third times a charm!).
All I can say is WOW! That thing drives like a sports car now! I guess I've been fighting the gear box for almost two years now, and I never would have suspected it if I hadn't had to replace the pump because the reservoir kamakazied onto the pulley.
For those replacing the box by themselves, I found that it worked great to put the nose end of it on a floor jack, rest the body against the tie rod and connect the lines before using the jack to raise it in place.