The Stovebolt Site Forums The Shop Area General Truck Talk 1952 Chevy Truck behind the seat fuel tank

I would think that for the tank to be leaning back , the lower front would have to move forward.
In my truck there is barely 1/4” clearance between the front face of the tank and the flange of the seat frame.

Or–-
Maybe the OP needs to place a soft interface between the back of the tank and the cab wall stiffeners to bring the top forward. (I did that.)

Pictures sure would help.