Ford C4 bellhousing differences

I have seen that Ford used smaller C4 tranny bellhousings w/ 10 1/2" bolt patterns and larger ones w/ 11.4"bp. Does anyone know which size is prefered for dependability and performance or is it just a fit issue?

 

It's more of an issue with case fill vs. pan fill....with the exception of the Mustang II/Pinto which had transmission tunnel clearance issues.

 

Have found this a great help:

http://www.mustangcentral.net/tech/c4.html

 

Great Link! Thanks plumpcars.