Interesting, was that the original diff in that trans or was it a replacement? That could suggest new-ish phase2 center diffs will have the c-clip rather than the cir-clip. That c-clip looks like it is the same groove thickness as the cir-clips used prior.
I have not bought one of these in a long while. Has anyone bought one thorugh service parts lately....what design clip was installed? I would imagine that a change like this would be released as "use up current parts first".