haha. i don't worry about swaps anymore, it's just so much easier to, plus all the tanks will work well for our needs, and sometimes they will let you pick which tank you want to swap with. although, the places i've gone to give me the option of filling, but it will take them a week or so - they just tag my tank empty, and then when they get everything else filled, they fill it to, and then call me when it is filled, and i get my same exact tank for the same cost of a swap. too much time. i'd rather just get a different tank. right now i have one tank that was made in 1947. still in excellent condition.