Torsion bars can wear out, just like springs do. If the tension bolts at the back are in approximately the same position side to side, and the front ride height is noticeably different, the bar on the lower height side has lost some of its tension. You can adjust the height, but the fix will be very temporary. Those torsion bars are extremely difficult to find unless they come off a salvage yard vehicle. New ones just don't exist, it seems.
Jerry
