The tank design I posted will occupy the same space as the original. The same straps are reused to secure this tank to the chassis. It holds approximately the same amount of fuel as the original.

The only difference you will see... the top does not include radius/rounded corners. It cost more to add the radius and they serve no purpose on the top side of the tank. The radius is on the bottom corners to allow for reuse of the original tank straps.

Jealous you did an LS swap.