Which r&p and carrier does gm use in those transaxles? You'd think it was sourced from one of their live axle lines?
I'm not sure, but its crossed my mind. I have a couple guys locally I may try to get a final drive from and take some measurements. From what I've experienced in the GMC community, most people are happy to pay a few to figure this stuff out. Not a lot of critical thinking and an awful lot of followers. That is starting to change (thankfully). Some of the newer generation (like myself) to have found this platform are starting to question the old guard and they HATE it.
If I had a dollar for everyone of the old guard who has said some variation of, "You've done it now. You gutted it and you'll never get it finished, because no one ever does." I could actually PAY someone to restore it for me. Not like around here, where everyone is supportive of a good build. We might question methods and techniques, but very rarely do you hear, "Don't do it, you'll never finish." That is CONSTANT in the GMC community. Not very supportive.
From what I know about GM, they definitely cribed the carrier and Ring/Pinion from something. The question is was it something that there is aftermarket support for? Like an old 10 or 12 bolt? That would be cool.