The '62 and '63 are the same in dimensions, but because the '62 bumper is curved out, the edges of the light housings are narrow on one side. It would seem that for a '62 Pontiac, even left and right lamps are not interchangeable. I had a burned bulb in one but when I tried to replace the bulb, the lamp socket crumbled from corrosion. I now have a '62 lamp on the left side and a '63 lamp on the right side, and I don't think anyone would see a difference unless they were to look real close.
For several months there have been a pair of lamps on EBay.