it just feels like an old worn out steering box with a little play in it.
That tells me you (for whatever reason) do not have enough caster angle. Not yet anyway. I'm still not convinced 6 degrees is right, but it might be. It sounds like too much to me.
Having said this I'm assuming you have checked the toe-in setting. You need to do this, but really what you're describing sounds more like caster. In a minute I will tell you how to solve this whole caster riddle if you want to do it. First, if you have
too much caster, your truck will be hard to steer. You're having to lift your truck up every time you turn it. If you have
too little to no caster, your truck will steer easy as pie but it will wander around all over the place and this can definitely cause it to feel like the steering gear is loose. With not enough caster or no caster weight and gravity force your pivot points downward perpendicular to the ground and there is no reason for your front wheels to want to center themselves. The faster you go the worse this gets, by the way.
In high school a friend bought a truck with this same problem. You could steer it with one finger but it would roam around everywhere. Scary to drive. He didn't have the money to have somebody look at his front end, so here is how we figured out what angle he needed and you can do the same thing: Starting with no caster at all, we took small bolts cut off to a length of about 1/4 inch (behind the head). We made 4 of these for each try starting with some which were larger than the shims which had been in the front to begin with. We would loosen the U Bolts, jack the truck up so the axle fell away from the spring and poke those little cut-off bolts in at the back (2 on each side about a quarter inch in from the edge of the spring). Then we'd tighten the U Bolts and drive carefully down a smooth road for a mile or so. Then we'd try with slightly larger diameter bolts making certain the center pin was still catching and we kept repeating this until the truck became too hard to steer. We figured this was our upper limit. Then we backed off until we found a thickness that would cause the truck to drive straight but not cause it to be too hard to steer. It took a while to find that point but you'll recognize it when you get there. Then we knew the shims had to be the same thickness as those bolts in the back tapering to nearly nothing in the front and he got the FFA teacher to help him figure out how to make some.
Good luck!
Jon
