I believe 8" and 9" small bearing pattern convert the same. I did it with Crown Vic parts http://www.jalopyjournal.com/forum/showthread.php?t=358587 but this might be easier: http://www.ebay.com/itm/Ford-Mustan...Parts_Accessories&hash=item5ae45ce81d&vxp=mtr Here's another: http://www.jalopyjournal.com/forum/showthread.php?t=569272
Still trying to find out exactly which 9" I have but it's large bearing with a 2" offset which seems to be the problem with the common swaps.
I used a kit from Speedway Motors that utilized caliper brackets that had to be welded on to the axle tubes, Wilwood hats and rotors and the old Eldorado metric rear calipers with the parking brake. My rear end was from an early Bronco with 11X1.75 brakes and had a 1 15/16" offset, I couldn't find a bolt on set to fit. You can save a little cash if you substitute cast iron rotors.
One of these should work - http://www.ebay.com/itm/DISC-BRAKE-CONVERSION-KIT-FORD-9-NINE-9-INCH-REAR-END-/290580317992 http://www.steeltechsolutions.com/REAR_DISC_PAGE_CODE.html http://www.steeltechsolutions.com/REAR_AXLE_ID.html http://www.tsmmfg.com/2500.htm http://nineforddiscbrake.blogspot.com/ http://shop.holcombmotorsports.com/category.sc?categoryId=321 http://www.9inchfactory.com/brakes.shtml