LXi Chassis Parrt Number List

[patticake]

Actually, it keeps the axle from moving side to side. It may not be much but it can. Think about what is holding the axle to the frame, some air bags, some rods that go from the axle straight ahead to the frame and a panhard rod to keep the axle from moving left or right. Plus the shock absorbers. That's it. The rods that are parallel to frame and the air bags keep the axle from twisting up or down, at the pinion(where the drive shaft bolts to) depending on whether you are on the throttle or not and how much throttle you are giving from a dead start. The air bags also support the vehicle instead of a leaf or coil spring.

Now that I confused you enough, on the ends of the rods that go forward there are also bushings that can wear causing problems. These rods are also on your front axle.
The problems you are having need a GOOD frame specialist in heavy duty equipment. Check with some charter bus companies in the area where you are or where you are going. Most truck guys don't want to fool with a bus, cause nothing is easy to access.