Hello! I planning to match a 700r4 to my nailhead on my '58 Super. since I'll get rid of the whole torque tube, my question is ; What rear end is more likely to be compatible ?
You could alway use the stock rear end and just switch out to an open drive third member from a '61-'62 fullsize Buick or a '63-'65 fullsize Buick thrid member if you have the axles resplined. http://www.v8buick.com/showthread.php?t=192673 Then you just need something to locate the rear end once the torque tub is gone, like '60-'72 Chevy truck trailing arms.
Here are a couple of more threads you might find interesting: http://www.jalopyjournal.com/forum/showthread.php?t=144403 http://www.jalopyjournal.com/forum/showthread.php?t=449031