Just wanted to let you know about an experience I recently had. Maybe it can help you out. :
I have owned my 2004 C5Z06 for 6 years now. I got it new. When it was new I noticed that the drivers rear tire stuck out 1/4" more than the passenger side. It was not that noticeable so I did not worry about it. I added my wider 11" CCW's that stick out just a little on both sides. That's when I really noticed the extra 1/4". I did not like it but it was not hurting anything so I left it alone.
Recently after I added my Coil overs I started to notice a little bit of tire shine on the inside of my rear fender. With the coil overs longer travel my tire was touching my inner fender lip. Now this issue got my full attention.
I did not want to damage my rear quarter for sure. I started to search around about this issue and found very little. I then found a post in the C6 Z06 section about my exact issue. He has a new C6 Z06 and the dealer said they can not fit it. I thought that sounded like complete BS.
In that post there was a fellow that said he fixed his car. I started to PM him about the issue, and how he fixed his car. Thanks to him I got my rear set up so that my drivers side tire only sticks out a little over 1/32" more than my pass tire sticks out. It was 8/32" before I fixed it. This should cure my inner fender rubbing too !
I found out that the rear cradle has alignment pins press fitted into it. The alignment pins insert into the frame during assembly as they mount the cradle to the frame. What I found out is that the hole in the frame that the alignment pins insert into are TWICE the size of the alignment pin itself ! No wonder all of our car's are a little different.
This is an issue on C5's and C6's....
What I did to fix my issue:
1.) Raise the rear of the car with jacks on both sides (not under the back lifting the rear cradle). Place jack stands under the car for safety.
2.) Remove the 2x bolts holding the rear diff to the cradle. (re-tighten to 37ft/lbs after).
3.) Loosen the 4x bolts holding the cradle to the frame (re-tighten to 81ft/lbs after). Let the cradle down approx 1/4" or so.
4.) I was then able to use a pry bar to push the cradle to one side that got me to the position where I wanted it. Measure the wheel distance on both sides frequently to see your progress.
5.) Try to make sure you push the cradle over straight. Measure to make sure one side wheel is not pushed to the front of the car, where the other side towards the back of the car. Keep everything as square as you can.
6.) Note... I'm not sure I understand the logic in this, but to make my drivers tire move in towards the center of the car, I had to push my cradle towards the drivers side. Don't ask me why... I don't know. haha. I just know it worked.
7.) R2e-tighten your 4x cradle bolts to 81ft/lbs, and re-install your 2x diff bolts and re-tighten to 37ft/lbs.
8.) Lower your car, and verify your changes.
9.) Get an alignment ! ! !
Hope this helps someone !