There are two 4.805" retainers. One has the 3.7" bolt pattern and one has the 4.16" bolt pattern. The one with 4.16" pattern bolts right up to the OD transmissions, that's how you can put one behind a big block because they never made a BB bellhousing with 5.125" retainer opening. The later 833's had 308 bearings just like the OD's.
