Agree with the others---it would be nearly impossible to install the shock crossmember in wrong--maybe too far forward or back---but not 4 to 5 inches too low on the frame---not possible unless it's my car--

. You got the wrong shocks would be my guess. One question---the leafspring perches (mounts) in the back--if you wrenched those down so tight that they locked the leafsprings into their highest possible position when you installed them--(perches would be angled pretty extreme --pointing rearward towards rear of the car), maybe it's possible that you have brought the spring up to its highest possible spot and the mounts back there are holding them in that position. You probably know this already, but they should be able to move. Just a thought, and probably not, but thought I would ask. I had something similar happen on mine once---let us know the outcome!
Doug