Hey Detroit,
Find out whats wrong with your truck for sure and let us all know. Most of us will bend over backwards to help you keep the old girl going. As far as the axle goes, there should be plenty in salvage yards or right here in the swapmeet. That rear diff probably has the same axles from the 40's well into the 80's. Depending where it broke, it may even be repairable.
The Gas tank is another story. Where is it mounted? If it's in the cab, start ordering catalogs out of old truck magazines, almost everyone carries one. If it's a side mount, I took one from a 75 GMC pick-up and mounted the brackets and all to the side of my frame. Either way, if there's a will, there's a way,
Scott
