slowmosu did that on his rear engine buggy, but it was more or less done to run the pinion backwards to get the axles to spin the right direction with the rear engine.. I do believe they still used a small bearing thoughI know this isn't of much help, if any...
But someone on here did a mod where they removed the small bearing to run large bearings on both ends. I think they had to machine the pinion, but I don't remember. I can look at some of the builds that it might be in tomorrow, but you'll probably have an answer by then. Perhaps someone knows the build I'm talking about and could link it.
Sorry, never taken the upper half of the differential apart... just the bottom.
Good luck to you.