I'm trying to put my newly rebuilt driveshaft assembly into my 1100 engine.
The inner cv wont go together.

The pot joint and ball race are each 64mm extremities, and the balls are the same size.
The outer cage does look physically different.

Is it just the outer ball cage that's different, or is everything else different too?

if I remember the cage can be put around the wrong way. Check that out.

Nope.
Two different cages. One twice as thickly walled as the other.
Jobs done now.