I found out the hard way that the keyed gas door locks are for looks only and just a visual deterrent for a thief. There's a plastic piece on the key cylinder that can break if the door is pulled on. I broke one on a customers truck and was forced to use the one from my 99. I then broke the second one while installing it onto the key cylinder.
A simple run to the salvage yard should be the cure...wrong. Nothing. A call to dealer and I discover a new one is $80! Ouch! I end up buying one for the customer's truck and now I have a truck with a gas door that can flop around.