I have been trying to install a rear disc brake kit on my '68. My measurements came closes to large bearing so I ordered a large bearing kit. Holes did not line up. Summit racing said I needed a small bearing kit. They sent me a Baer kit for small bearing. Holes did not line up. No tag or ID on the axle. It is a 9" with 456 gears. At this point I would have to believe this is not the original axle. The person I purchased it from Drag Raced it running A LOT of nitrous. I pulled all of that off. I don't have a nitrous budget. The flange (attached) is Ford and my measurements are as good as I could measure from center hole to center hole without using a measuring caliper. So, if anyone could ID what differential I have, It would be really appreciated. The last kit (small bearing) fit the 8 and 8.5 axles from Ford. However my housing matches up to 9" and being ¼ mile car in it's past, I understand going with the 9" posi. Thanks in advance for any help!