I thought I explained it pretty clearly in my previous posts Mickey. My tank is over 20 years old and I need a new one. A new one will cost me $200 plus purge and filling as opposed to a $15 exchange at Walmart. Plus the convenience of exchange over refill. You can always find a Walmart or Gas station exchange, but finding a filling station is a bit trickier if your not familiar with that area.
I did find an easier solution, I am going to get a longer hose, sit it on the truck tailgate when not traveling and chain it down so nobody steals it!!