OK, i dunno if this has already been covered, but what i have read seems most are seeing the rear toe issue in the hubs? On my car its the chassis. Simple test... get a piece of paper and a ruler and a pencil. You can strip your chassis completely apart, but isnt necessary for this test. Lay your chassis on the piece of paper with the rear bulkheads mounted, but nothing assembled on the top side, no shock tower mount no top plate, ETC. Use your calipers and measure the distance between the two halves at the front and back and take note if they are NOT the same... the rear of the rear bulkheads are farther apart on my car 1mm than the front of the rear bulkheads. Now the only square section of the chassis to measure for comparison is the sides, to see which side is actually off... the left or right of the rear bulkhead. The sides do not extend far enough to take a measure from the bulkhead F/R to the outside flat of the chassis, so you use the ruler and the piece of paper to "extend" the sides of the chassis to get a measure from each bulkhead to the line drawn. This difference when compared to the centerline of the chassis will tell you if both sides are off, or if it is actually only one side that is off. Basically it looks as if the chassis moved as they were drilling the holes for the rear bulkheads to mount. The left bulkhead is about .6mm off from the center, and the right bulkhead is about .4mm off from the center (on my car). The front half of the bulkheads are centered with the center of the chassis... but separate gradually going back, they basically add toe, but unevenly L/R. I found no irregularities in my rear hubs. They add identical toe when compared to the arm only.
To be sure, i measured thickness of the bulkheads and that each screw hole in the bulkheads were centered... otherwise this test would be flawed. Im sure if everyone else took a few minutes to check their cars we could nail this issue, and inform Xray so they could take care of it accordingly.
Hope this helps in some way...
- DaveW