Found the measurements.

From the front body mount (on the front subframe) across (opposite side)the car to the front eye bracket of the rear rail it's 75 7/8".
From one eye bracket across to the opposite rail eye bracket it's 33 1/2".
From the rear shackle mount across to the opposite shackle mount it's 42 7/8".
from the eye bracket across to the rear shackle mount of the opposite rail it's 66 11/16".

These are measurements from a page of the assembly manual that was posted on this site on 8/20/2005.
I printed it out when I was doing my rails.

Hope this helps.