I don't know what the differences are, however the ebay units match my LH STD rotation distributor tag exactly except for the date code. E5JL-12100-CA # 7020S If your needing springs this may be the way to go as I suspect those are the same for RH and LH rotation units. Perhaps I'll pick one up and compare it to my original.
Hard to make out but it's the same.
1989 MasterCraft TriStar 190 SE