Standard GMC cab to extended
 

Hello,
As members may have read before, I have a '64 GMC 1000, standard cab. Want to remove the seat tank and extend the seat back. I have a small rear window and wanted to know if anyone has cut out that part that would normally cover the top of the tank, under the window?

By removing this panel, would it take away from some of the structural support of the cab? By looking at it, I feel it would allow the upper back support of the seat rest to go back another 2-4" at best, which may, in turn allow the base to be modified, or install another type of bench seat to go back as far as possible, gaining more leg room. Visually, I don't think it would make me have the rear door jamb covering my side vision.

This is the biggest change I would need to make, is for comfort while driving this truck. Finding room for the new fuel tank is no problem, but gaining space in the interior...this is the tip of the iceberg if I decide to keep this truck or not. There's the love...and wanting to completely restore it but why drop the money into it when I can't comfortably drive it?

With my personal size and height, it's difficult to operate cramped, riding the clutch, lifting from accelerator to brake...let alone reacting quickly to be safe in it if the "other guy" on the road screws up.

Thanks for the input!