the spring seats are available from Mopar for Approx $12 , you would need to cut the old ones off , set the pinion angle correctly at 5-7* nose down & weld the new seats on , what I suggest is to mock everything together with the diff centered & the U bolts loose enough to correct pinion angle & tack the seats into place The pull it back apart & weld the seats into place
The part # for the seats is P4120074
