Drivetrain Driver's Side Axle Shaft Not Seating Properly In Diff

Hey all, my name is Steve and I'm new here. Technically I do not own a Mustang II, but I have an 8" rear end from one that's going into my Pinto. I figured this would be the best place to get help. Thanks in advance...

I had the axles out to be drilled for 5 x 4.5" bolt pattern, with new bearings pressed on. The passenger side axle went in just fine, but the driver side will not seat all the way in the differential, which is a 3.25 ratio with posi. I removed everything from the housing, and noticed there are two gears in the driver side of the diff, and one is misaligned/offset with the other (see picture attachment). I took depth measurements from inside the differential and transferred them to the axle in Sharpie, so I know the misalignment is causing the interference.

Since everything spins together, I have been unable to align the two driver side gears - can anyone help explain how to turn one while preventing the other from turning with it? Thanks again...

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To the best of my knowledge, this is a rebuilt factory unit with the Trac-Lok differential. After reading your reply, I got the idea to look through the Ford Master Parts Catalog. According to the diagram, it does appear that there are two toothed parts where the axle shaft splines should mate to. One part (4946) is called the 'Rear Axle Differential Gear Clutch Hub', and the other part (4236) is the Rear Axle Differential Side Gear, which appears to sit inside the Hub.

Still hoping someone out there can explain if it's possible to rotate one and not the other, without having to disassemble the thirdmember.

That's a great idea, thanks for the tip! I'll repost my question there.

For anyone who comes upon this thread, perhaps with the same issue as I had, it was resolved. Click here for the solution.