This is a good picture of a reverse light going through the grommet. CAUTION the wires for the reversed light plug are reversed! The black should be where the black-white and the black-with needs to be where the black is.
The diagram I posted in the upper left shows for standard and automatic reverse light. #7 and #8 connector. The bottom plug The top plug is for the wipers. There could be a difference in the location due to build date or plant. Mine being a Nov 7 71 build date it's connected to the plug not...