R3 has already linked to my article about how to make them do double-duty as side marker lights and side turn signal repeaters—if you do this, first you'll need to enable the parking lights staying on with the headlamps. On (most) pre-1968 vehicles, the parking lamps do not remain lit when you turn on the headlamps. For 1968, this was changed so the parkers stay lit with the headlamps for safety (in case of a headlight burnout you still have at least some visible light on the burned out side of the car). This is easy to retrofit: remove the headlamp switch and unplug its multi-wire connector. Put a short piece of 18ga wire between from the "P" to the "R" terminals on the headlamp switch body, right down at the base of those terminals. Make sure the ends of the jumper are neatly tucked so they won't touch any adjacent terminals. Solder if you like. Then push the connector back onto the switch, on top of your new jumper wire which won't get in the way, and reinstall the headlamp switch. This will emulate the wiring setup of '68 and later cars that keep the parking lamps lit with the headlamps on.
Meanwhile,
here is a retrofitted '64. Pics up top; plus search the page for
nifty to go to the side marker details some lighting nut put in the comments.
If you don't like those L482 units, another one that suggests itself is an L734. Not hard to find; I am pretty sure I have new ambers and reds on the shelf.
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Whichever (legitimate) lights you choose to install, there are tricks and strategies for making them work better; PM me if you want help.