What are you measuring from to say one side is 1/4 farther forward than the other?
If you measured each side against the spring mount, your frame could be out of square. That could cause what you are seeing, depending on the reference measurement point.
I would recommend picking a point that is unmodified on your frame (such as the rear spring hanger location) and measure from there to the opposite side on the rear.
So as an example, measure from the front-left spring hanger to the rear-right. Then measure the front-right to the rear-left and compare those numbers.
