I'm putting one in my chevy, how do you center the Ford offset center section? The rear looks off, are the tubes different lengths?
Some have the yoke centered, which makes the housing look off-center. Yes, they have different length tubes. Some have the housing centered, which makes the yoke off-center, but it looks good under the car.
It doesnt have to be centered wont affect a thing if you want it to be in the center than you will have to cut one side, and have that sides axle cut too.. a lot of work for no benifit My 8" (same thing) in my A isnt centered..cant see it, and even if you could its not a big deal.
Just as Relic said, depends if the rearend is yoke centered or housing centered. Sounds like your donor 9-inch is yoke centered.
The housing centered ( offset yoke) is a great thing for those builds where the driveshaft winds up being parallel. The offset helps the u joint
Here are some Pictures and different cutaway views of 9 inch axles. These will help you and others to understand, the pinion offset. When shortening a axle, put the pinion on center. Since you are going to rework the length, just get the axles made to compensate for the new pinion offset. http://www.difftrans.com/index.php?brand=default§ion=diffcons The offset, makes the ujoint, needle bearings to rotate around the joints trunion. .