Wire harnesses. When did the design change?

I sold a 1965 main bulkhead plug to a member here. I probably sold it too cheap!
I looked at the harness of a 66 Dart today. It had 3 snap on plugs like the later cars do.
The buss bar design seems like a better system though. It probably had less corrosion buildup compared to the male/female Packard connectors the rest of the cars had.

Thanks for the help, guys!