need help with my 4 speed tranny

You're going to have to get an overdrive bellhousing because the O/D's bearing retainer size is 5.125. The 833 O/D is basically the same as the regular 833 except for the O/D part. It should be the same case as the old 833. The newer 5.125" O/D bellhousing shouldn't be too hard to come by for a small block. Are you sure it's a C-body trans? How many shifter mounting locations does it have? And welcome to the site by the way.