A followup to my other review. With the correct spacer I give this a five star rating. Fit great and runs like new. I wish the spacer info had been available and all three of my available axles hadn't been rare. All of my axles were rare so it is more common than believed. Definitely measure the brake offset before committing to pressing on bearings, etc.
Installed this axle into a 8", 28-spline, '65 coupe. Got a one star rating because it looked good in the car and appeared to be nice quality. Lost four stars because it didn't turn. Superior Axles' website clarifies the problem as the brake offset dimension. A percentage of Mustangs require a 7/64" spacer that only they sell. It is not mentioned anywhere on the internet to be the case. Ads state it is a direct replacement with no modifications needed so I had it installed with no clue of what to look for. The drum binds on the brake backing plate and drum shoes. It actually left scratches in the drum from the metal on the brake shoes. You have to check this measurement between the new and old axles to know if the spacer is needed. This requires having the new one already and pulling the old one for comparison. Double labor and hassle if you're not lucky.