That would appear to be a 65 only part. 65 is the only year that had twin lights on each side.
As far as physically fitting, I'm pretty sure it's a bolt on but to put it on a 64, there would have to be some changes made to the outer tail light panel on each side to install the matching lamp to the one in the trunk lid.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars (now converted to a "factory" 4 speed)
