The centering valve on older Mopar steering gears (most likely your problem) is a 2-slotted hole under where the high pressure hose flange bolts to the box. Test for it by starting the truck in neutral. If the the steering wheel starts to clock by itself on start, even slightly, that's your problem.

 

Try this with weels off ground as well .... also try to steer with out tires on ground and see if that changes anything ...

 

I haven"t seen that, but I'm interested. I've seen the brace disclaimer pretty much everywhere I've seen the box for sale.
I also came across this nice little page if useful trivia off Borgeson's website which seems to explain it, and more:

http://www.borgeson.com/troubleshoot...e_Box_Tech.htm

 

Mine is an 2003 dodge 2500 4x4, i removed the front hubs to check mine the short shaft going into the hub would not bend down in one direction but did the other, it seems the u-joints clock them selfs a little every time you turn the steering wheel although they are not being turned by the 4x4, which caused them to bind, on the 03 dodges the u-joints turn all the time on stock trucks but i switched mine over to manual locking hubs which contributed to the u-joint problem, i think they would of stayed loosened up if they turned all the time but the wheel bearings wear out pretty fast on the oem setup, so im still staying with the manual locks and juct pay more attention to the u-joints now, I'm betting its the u-joints on yours 2, when you do find the problem keep us informed.

 

Sounds like a stabilizer issue to me

 

Pretty sure a stabilizer issue would affect both directions.
I'm leaning away from the u-joints as well, unless you've pinned the fork in your 4WD actuator. Both my axle u-joints were quite literally falling apart and I never felt a thing.
My (hyopothetical) money is on the gearbox.