Point of clarification - from # 2 in this post:
https://xoutpost.com/1024694-post10.html
"2) The manual flanges will go right into the auto diff, and my car now has one of each in it, since I had an episode with one of the new auto CV bearings puking its cage and ball bearings all over the garage floor. I got one from ECS that was supposed to be VIN matched to my car, which was really huge (length and splined diameter) and did not fit either differential."
From my research in realoem, this shouldn't be possible, but it's exactly what I was hoping to do - put manual flanges (stub axles) in the auto differential.