A230 A833 od

I believe the OD transmissions have the largest bearing retainer diameter (5.1) of all the manual transmissions.
I don't understand what that means . The bell doesn't have any sort of rings or seals right ? It just bolts on ? But looks the same a 833 and imf trying to find the thread where someone told me I could use my slant 6 a230 bell on the a833od . But brewers just told me they don't think they are the same .