If you plan to keep the tank in the cab, I suggest replacing the tank. There are sources that sell OEM or reproductions for your '64. Try chevyduty.com and LMCtruck.com. If you plan to relocate between the rear frame rails, Classic Industries, Classic Performance Products and several others sell the custom fabricated stainless steel or aluminum tanks, sending units, filler assemblies and associated hardware. I am in the process of doing the swap on my 1966 C-10. Classic Trucks has a tech article on their website, as well. You can determine the ease of installation by reading the tech article. CPP also has a play-by-play tech article on this swap that is very informative.
