No, because the bearing pockets for the outer race of the carrier bearings are a larger diameter. The smaller bearing size is the far commoner one found. One vehicle which often seemed to have the bigger, better nines was the Torino, around 1970.
If you are experienced in setting up gears, I need not go into important specifics, but in case you are not, and plan to do this work yourself: Most important aspect is pinion bearing preload, followed by diff. bearing preload. After that, tooth contact pattern along with correct backlash. The nine inch is actually one of the easiest to set up, due to the removable pinion carrier. 8.8 for example, pinion has shims to establish both bearing preload as well as gear location.To change them if "playing by ear", without depth gauges, the diff. carrier with ring gear must be removed to extract the pinion. On nine, it comes out the front. Most others involved pressing pinion bearings on and off the gear to access shims; nine has them between the case front and bolt-in pinion retainer. Those 5 bolts are Grade 8, and deserve to be torqued appropriately; insufficient bolt load allows shifting of gear tooth location, which must be held to a minimum.
Pinion bearing preload is done two ways: "crush" sleeve, and solid spacer. The solid way is better, more sensitive to error in set-up, though. All Ford "High Performance" vehicles came with solid spacers. My buddy back in the days of the first (1963-1/2 Ford 427), actually cracked his carrier in two, split vertically top to bottom!
Mistakes can be made. Been there. When installing carrier in case, do not leave carrier bearing cap bolts slightly untightened to allow easy rotation of adjustment rings (which are threaded). Doing so allows shift of gear location when torquing them. That mistake cost me a new set of gears, scored unimaginably.
Finally, let's say you have set up to your satisfaction, good pinion and diff. carrier bearing preload, good backlash (shoot for high side, 0.015" OK), tooth contact pattern centered, especially on drive side. Wipe all tooth surfaces clean and dry, fasten the carrier in a strong vise, grip it by the bottom lip with soft jaws, grasp ring gear (use rag, sharp edges!) and rotate the assembly back and forth. Do that all the way around the ring gear. The "feel" should be smooth, not raspy, should make little or no sound. If the is a scraping feel, it is almost a guarantee the gears will run noisy. Getting it "smooth" might simply involve changing backlash a bit, usually a bit more, but sometimes the other way. OK if contact pattern on drive side moves slightly outward from center of tooth.
Avoid: nine inch cases very early, 1957, '58 with very large pinion seal, about 4" diameter. Any questions, feel free to ask! imp
