were do i find a reserve tank for a 1972 f250 or how should i go about moving the tank out from the back of my seat to some where else thank you both my tanks are rusted and it would cost 400$ to clean and coat the one behind my seat

 

Ithink Northern Tool has a tank that isn't too expensive that would fit in the front of the bed. Not sure if it is DOT legal though.

 

You can buy new bolt-in replacement gas tanks from several of the usual part suppliers for about $200. Why mess around with repairing the old tank or modifying the installation?

 

so i got my lmc book then i ordered the side mount gas tank.
It was about $200 with shipping got the old one out waiting on more parts
and some por 15 thanks for the input