Welcome to the Stovebolt site R. F. -
47-54 bell housings allow the T-5 to bolt directly to the bell housing. If your talking about an earlier year, the T-5 could bolt to the bell housing by use of an adapter or you might switch to a 47-54 bell housing, but other things begin to need attention such as the mounting of the brake-clutch pedal setup.
There has been quit a bit of discussion on this subject and you might want to run a search for some of the discussion or let someone else chime in right here with comments.
