The stock drag link will work at 5.5". If you're shocks are long enough you could max out the joints, but just check them for wear occasionally. A dropped pitman arm is a good idea, but not the 3" SJ, just the 3/4" lower ZJ pitman arm. Even that small amount will help the drag link joints to not bottom out, plus I think that a dropped pitman arm actually lines up the drag link and track bar better than the stock pitman arm.
With a tall lift, like 5" plus, there are more threads showing on the end of the drag link next to the adjustment collar, since the collar is adjusted out more to center the steering wheel. The stock drag link has a tendancy to bend at those threads with hard use, especially if the steering stops aren't adjusted right and the steering isn't centered. Have someone turn the wheel while you check to see if there is still some turning left when the knuckle hits the stops when turning to the right. If there is some turning left after the stops are hit, it will compress the drag link and there is greater potential for it to bend at the threads, so adjust the collar so the steering is more centered.