I'm having trouble finding a driver's side rear backing plate for an '83 with drum brakes. I got one off an '84 only to discover the bolt pattern for '84 and '85 are different. I was told the '79 and '80 is different too and only a backing plate from an '81. '82 or '83 will fit. Now someone has one from an '80 and says they're the same from '79 up to '83. Before I buy this one I'd appreciate someone jumping in here to confirm what fits what. Thanks.