You replaced your used box with a used box, you don't know the history of that used box. Your best bet is to find a new or rebuilt box, check all your tie rod ends, idler arm and ball joints. I know it cost alot more but it should drive like new when your done. With my lift and 31s I replaced my ball jonts every 80,000 miles, the original tie rod ends and idler arm went 180,000 but when they needed repleced your could feel it.

Dennis

95 Sportage, gone but not forgotten.
98 Jeep TJ, 4" Zone springs with RC Long arms, Ford 8.8", 4.56 gears & Detroit locker rear, D30, 4.56 & Detroit Trutrack front.