I don't know about 64 but on my 67 I was able to make a pattern of the connector and cut a simple sheet metal plug, which clips into place with the original connector clips, then just a hole and grommet
For hazard lights on that old girl you need something "special" or else conjur up a switch out of a 67--69 which is a separate toggle, mounts to the dash
HERE IS HOW the 67 hazards work.
You have turn signals and the switch and the turn flasher, just like your 64.
You have a hazard flasher (there are 2 flashers in the car) that flasher is always hot and feeds the hazard toggle WHICH IS a special switch
That switch has 4 terminals. When off, none of them are interconnected. When on, all of them are interconnected.
One pin hooks to flasher, one pin hooks to brake lights power feeding into the TS switch, and the remaining two splice into the left front and right front turn signal switches
Simple.......if you have that switch.
Otherwise you'll need an aftermarket hazard switch, which used to be sold, to add hazards to an older car
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