Outer Limits 4x4 Board

A friend of mine has an RA rodeo and was playing tug of war with his brothers hilux.

Now when he accelerates the rear end seems to shift left and then when backs off it straightens back up.

Do they have a panhard rod that could be bent?
Or are they just held by the U-bolts on the leaf springs

Also could he have damaged the bushes in the springs thus causing this problem??

Any help would be much appreciated.

These things are leaf sprung in the rear. Maybe shackle bushes, u bolts or center bolt in spring broken allowing diff to move on the spring.