Main Caps for 3rd member

what most people don't know is you have to have the ORIGINAL main caps that came with any rear differential case whether it be-- Chrysler ,Ford , GM , Toyota --- these caps are line-bored from the factory -- same as main caps on an engine --- that is why they cannot be switched side to side when assembling a differential.
and why you cannot take caps from other cases to fit the one you have --- I see cases at swap meets all the time without caps -- nothing more than scrap metal -- stay away from these.