Were Mustangs the only cars that used the necked-down 9" housings? And, if so, how many years used them? And is this one of those?
If the axle bearings are the same size, the brake packages can swap between the 8" and 9" axles.Were the 9's put only behind Hi-po's? I can't see them putting them behind an A-code. The reason for all of my curiosity is that there is one for sale locally. I figure that even if the only real benefit is a better ratio, for what he's asking, I can't even buy a steeper chunk. Looks like all that was offered in a 9 was 3:00 and bigger. Currently running a 2:79. There's also the potential for a bigger brake package. Sell my clean, painted 8" and perhaps break even.
Here's what I have. Round back side with the dimples. The tubes taper down but not by much. I did have an identical housing that did not taper. For some reason the leaf spring pads are not in the correct spot on the housing I have.I’ve got an early 9” (57-59) in my 65 and it doesn’t have tapered tubes. Maybe it was a small/large car thing? Mine is a small bearing rear end.
Or you could just buy a reproduction 1965 or 1966 Mustang 9" axle housing. Both are available.Yes, the 9" in '65/'66 Mustang was standard equipment with the K code and was not available as an option with any other engine. Since it was only in the K cars there is a limited quantity of them out there.
That being said, you can cut the axle tubes out of a '65/'66 8" and weld them into a 9" center section and create your own version of the unique K code 9".