49-54 Bagged Chevy's-Driveshaft tunnel?'s

great pics & ideas, this will help me a ton!

 

look here
http://www.jalopyjournal.com/forum/showthread.php?t=293280

 

I know this thread is kinda old but Imay need to do this in the next few days on my '51 Belair. I planned on using a 2-piece driveshaft but my dual exhaust is all tucked up level with my frame, which makes a center support crossmember impossible. How close can the bumper be to the ground before a 1-piece shaft requires tunnel mods?