LETS TALK GAS CAPS

First thing to determine is "if" your car has evaporative emissions or not. Look and feel around the filler tube in the trunk. See if there is a small 1/4" tube welded in, which leads down the filler, and goes through the gromment floor. If so, NON evap controlled, lean towards 69/70

If you DO have evap, no small tube, and your car originally (probably) had a tubular tank like device in the trunk for part of the vent system AND has a small 1/4" tube that runs along with the fuel line up into the engine bay, and (originally) connected with the "carbon can" setup