You'll find that very few of the electrical connectors used on these old cars had keepers/latches.
The reverse lamp switch moved to the trans sometime during 68 model run. For the earlier like yours, factory added a console wiring harness to this same connector under the dash. 2 wires for the floor shifter mounted reverse switch, orange wire for the lamp, and maybe a red wire for a lighter well were routed under the console. If you'll stay with that layout try to buy a floor shifter with a good switch on it. Shifters from some later models did have provision for mounting this switch even though the switch wasn't there. I dont know if that ever changed/went away or not.
If you change to a later model trans with reverse lamp switch there you will route these 2 reverse wires through unused ports at bulkhead connector and extend them along with the brown neutral safety wire to a different 3 wire connector down there.
