S10 Tank won't fit

[gregw98]

I am in the middle of a S10 transplant under my '54 five window. The front cab mounts are 4 inches and the rears are 3.5 inche tall. The stock S10 tank will not fit unless I do some rubber hammer massaging to the leading area of the tank. I am toying with the idea of a '65 Mustang tank, but have a question about cross bracing. At the rear of the S10 frame, there is a cross brace used to support the spare tire raising mechanism. It is located directly above the upper rear spring shackles. Does, or can, this brace need to be moved or does it have anything to do with the rear suspension support?