Thank you very much. So basically from the rear of the top quarter end cap to the rear of the rear of the base of the wing 3" to 3 1/2
Yes that is correct,...also the wing base itself is (should be) approx 17 1/4" long, keep that in mind for possible stripe placement, the rear cords (vertical trailing edges of the wing uprights) are parallel to one another, there's no taper when viewing the wing from the rear of the car, the approx measurement between the center of the rear cords, should be 60" top to bottom, be sure to check the cord measurements, as some Tona wings will taper at the lower section of the cords dimensionally wise when the uprights are bolted to the center blade on an unmounted wing, so you may have to loosen the wing assembly to take any proper measurements of the base studs, it's not unusual on any wing, original or repro to have the stud orientation, or bases angled/distorted, you'll just need to compensate the location of the holes on the qtrs, the trick is to measure as much as possible and drill once, otherwise you'll be making Swiss cheese of the quarters
mike