Ever since the purchase of my car a couple years ago i have noticed the rear end sat about a half inch more to the drivers side. A couple months ago i decided to try and fix the problem. I found that the driver side upper control arm portion connecting to the frame had dislodged the bushing from its seated original position and had been riding that way for quit sometime. So i purchased new upper control arms that were ford racing replacements. Upon installation i noticed that the problem hadn't been fixed. I had figured that by installing new arms and bushings it would re-align. It helped a little. FYI i only replaced the frame bushings, not the rear-bushings on the control arm because they check out visually. So i took another attempt at it. I looked over the lower control arms and saw no visual defects so i removed the upper control arms so that the rear end was free to be moved. I took a rachet strap and connected one end to the passenger side shock mount on the rear end and the other end on the driver side frame. I aligned the rear end and re-installed the upper control arms, but to my dismay, once the control arm had been connected to the frame, the rear end connection portion where the bolt goes through was 2/3's a hole off, and when i make the bolts go in the rear end goes right back to where i started. The only fix i can think of would be to purchase adjustable upper control arms. The only thing that doesn't make sense, if everything else checks out and its a oem direct replacement, why wouldn't they line up? Any help would be much appreciated.  

Perhaps you have some bent control arms. The previous owner may have been hit or maybe slid the car into a curb. Usually if a car is leaning, it's because a coil spring is bad.