Straightening a 8.75 rear end

Just got off the phone with the guy checking the rear end, much to his amazement , he said the rear end checks out almost perfect, said he hasn't seen one this good in a long time. Unfortunately this means I have a problem somewhere else. As the rear end wasn't square in the car. The ladder bars were the same length, but the rear was at an angle to the car. Guess I have to take a closer look at the mounts, and get measurements.