The Muncie four speed is the same length and uses the same 27 spline output shaft as the TH350, the PowerGlide and the three speed Saginaw manual transmission (as well as the newer 200R4 overdrive transmission).
All four of these are a direct bolt in as to the size of the tranny dimensionally. The TH400 is a bigger (taller, longer, heavier) transmission and it uses a larger 32 spline output shaft requiring a new front yoke on the drive shaft to fit it.
The 700R is three inches longer than the TH350 it is based upon (they did add a an extra gear in the tranny after all), but it uses the same smaller 27 spline out put shaft as the TH350, but it uses the TH400 rear transmission mount position that is already stamped into all B-body car's frame made from 1965 up to 1999 (you just shove the TH350 transmission cross-member back to line up with the new holes after grinding or sawing off the front lip to clear the TH400's tranny oil pan if actually using a TH400 transmission). If you have a 1958-'64 "X" frame car then I would recommend the 200R4 over the 700R4 as there are fewer size issues to make it fit.