I have a '73 Nova 2 dr coupe.  I have been playing around drag racing a couple of years.  I went to 28" tall tires from 26" and noticed the differential seemed to be set off to the right.  I started measuring fron the rockers to the driveshaft, the tires to the outer wheel wells, the tires to the inner wheel wells and to the "frame rails" attached to the body, etc.  All of the measurements confirmed the diff is set to the right 1/4".  This does not seem like a lot, but it is very obvious with the bigger tires.

I have found a couple Nova sights where I found info that when big tires were installed the passenger wheel lip had to be rolled for clearance.

Has anyone had this problem?  When I measure the spring mounts on the diff relative to the backing plate mounting flange, I found they were mounted 1/4" to the left, which would shift the axle to the right.

I am thinking of having the mounts cut off and rewelded so the diff will be centered.

Or is there something I am missing.
Thanks for any info on this, because last year I ran 10.67 at 128mph in the 1/4mile, and this year with some changes I am hoping to go faster then that

Does anyone know where I can get body/collision dimensions for the car so I can verify all else is correct.

Thanks again for info  

Interesting. I know when installing a 9-inch in a Chevy, you have to offseet the differential to get the pinion angle right.

I'd check to make sure that the rear subframe hasn't been tweaked at some point in the car's life. As for body dimmensions to check this, I'm not sure where you could look, but I'm sure someone on the baord will.  

all chevy's are that way. approx 1/4" difference on one pass side.  

What makes you state that all are 1/4" off to the passenger side?  I have been able to find some  dimmensions of the '73 differential. The info only shows dimensions including spacing between the spring seats.  But nothing showing one side different from the other.  

All the measurements I have taken, including "X" measurements from any points I could find on the vehicle to work off of, without having factory specs to work with, show the vehicle is square.

The one reply states all diffs are offset the 1/4", and that just boggles my mind, but I guess it could be true.  But it has nothing, at least that I can find, to do with the body or subframe, only the spring perches.

Still very mystifying to me!