ignition switch 63 dart

A locking cap with a key for a '66 and older A-body is not the easiest thing to find but not inpossible. I've seen a few on E-bay from time to time but they can bring pretty good money on an NOS one. They're not usually that hard to pick as most brands have a pretty simple lock tumbler. See if you have other gas cap keys on your ring that match the slot. Many times all it takes is a little lube and some wiggling of the key to get it to turn. You may have to try a few different ones but it's rare I have to try more than a half dozen or so. You may have to round up some from your wife, ked, and/or neighbors and friends but it's worth a try rather than run out of gas.