There are a couple of kits out there to do this conversion, but 55's had a gas tank door on the drivers side on the rear fender, at least my stock (well, except for the blown small block and Tremec 6 speed and 4 wheel disk brakes and a few other things, but the body is stock) 1955 210 two door has it there.
The 56 and 57's could be had behind the tail light from the factory.