[ZeGermanHam]

If you look at how the 9" center sections are constructed, you'll notice that they are offset to the passenger side. This means that the driver side axle will be longer than the passenger side. This is done to keep the housing centered in the car, not the driveshaft. Here is what that offset looks like in my '66 GTO frame.



If you center the pinion yoke so the driveshaft is straight down the middle, you will then offset the differential housing, which may or may not cause clearance issues depending on application. Personally, I'd just buy a complete drop-in 9" from Quick Performance. I'll bolt right into your F-body.

https://www.quickperformance.com/GM-...e_p_21573.html