those caps with the black and or chrome plastic " S " looking handle are after market ,at least here in the states,the factory caps have a straight handle both come painted or chrome,the difference in 62-66 and then 67 and up, the inner part that locks the cap to the fill tube is very different,the out cap appears the same, so since you have gutted the part that makes it different, you can get any A body side gas cap for stock apperance,but the handle is not bolted on like yours is,you would have to weld that nut on to the back of the cap, the factory handle is held on by 2 small screws on the end of thr handle,,not bolted to the center like yours is,,, hope this helps
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