72 Dual tanks valve

[4x4Bowhunter]

Looking for information on factory dual tank setups, mainly the manual vavle that switched between the in-cab tank and the factory auxillary tank.

My 72 K20 GMC has the aux tank but it hasnt been hooked up in years with the valve itself completely bypassed. So the vavle is rusted pretty bad and wont move at all.

Any input on where to go to replace this valve would be very helpful.

In addition, the dash wiring from the switch that operated the two sending units to the fuel gauge has all been removed. Can anyone offer any help with wiring that as well?

thanks folks!