This document seems to imply that many of the parts for a 722.3x and 722.4x transmission are the same -
http://www.ganzeboom.net/images1/ganzeboom/parts/Mercedes/722.3,%20722.4.pdf
Here's the tail cone portion
But there are some obvious external things that are different - for example the tail cones and the neutral safety switch.
I tried to look up the parts on Fastlane and see if the gasket was the same part number for both transmissions which would be a pretty strong indicator that the two tail cones could be swapped, but I didn't find these on the site.