I guess I'm still missing something here. Which would not be the first time...
I do know that if I split the case of a transaxle and made it race ready for whatever class that it may be in, I would lock it up by means of welding, adding gears, or fabricating a block for the bull gear and running a straight axle. There have been several posts on these procedures.
I maybe wrong on this but, if I am, I want you to show me on the track. We can talk about it all day long but when you pass me in the race, thats were it counts and I'll grow a bigger ear for that info.