I would ditch that track bar. Since you are not driving it on the road, you really shouldn't need it, especially with leaf spring packs that are that heavy. If you were driving it on the road I would still tell you to ditch that track bar because it is going to give you some VERY weird steering characteristics as the vehicle moves up and down, and you would likely end up somewhere you didn't want to be. Offroad it is going to limit your suspension travel as your springs want to travel straight up and down and the track bar is trying to pull it to the side.
If you have loose steering it could be slop in the box or input of the box. Otherwise it is due to a loose joint, bushing deflection in the shackles/springs or deflection in your steering bracketry/contraption. Have someone turn the wheel with the vehicle off while you watch each joint for slop or deflection.