Inspection of a 904 torqueflite

There is a question I have.

I have a 1967 annulus support for the ring gear in the low gear assembly that was supposed to replace the 1976 support I broke when I put that thin bushing in.

These two supports have the same part number. However: the teeth on the 75 are 1/16 longer than they are on the 67

Go to the 87 support. Different diameter and part number .
The teeth on it are the same height as the 75.

What’s the deal with this. I don’t want to build the 904 until I know if the 67 support will work in the 76 of if I should find a support that is identical in measurement

What I would guess is that it won’t work because the 76 is the 4/4 and the 67 is a 4/3. That extra height is set for that extra clutch. .....
Why do they have the same part number then?