Car is walking side to side...
if you have stock lca's and panhard bars the rear end cant be out of square unless any one of those components is bent, also the car wouldnt sway if they were bent but pull constantly to one side while getting worse with speed.
the axles would have came out of the rear end within the first mile without the c-clip installed. thats not your problem.
i think your panard bar is loose or missing. make sure you have an upper and lower and all fasteners are tight and intact.

