Pre-Drilled Bodies

I usually order my bodies pre-drilled because I haven't aquired all the tools I need to do my own. A good buddy of mine told me I needed to check them before I spend a bunch of time on them to make sure the rears migrate out towards the head. I did this last night and two bodies did not. The rears did not migrate out. If I run the car in reverse they do? Any thoughts on this, and is there something I could do to fix this? They are all drilled rears canted for SP and SS.
 
rotate your axles 180 degrees and run them forward.

my gut says your axles aren't straight. (+1 to what JAC said)