dual tank lines

[oldgreygoat]

I got a 86 single cab dually this week. Its an old farm truck, and pretty well ragged out, but its fixable. the p o has taken the fuel lines off the tanks, and installed a gas line from the left tank to a electric fuel pump, bypassing the fuel pump on the engine. the fuel lines that go to the switchover valve mounted on the frame have been taken off. I want to put this all back the way it came from the factory. Does anyone have a diagram of where the lines go from the tanks to the valve, or pictures of this setup. I looked in a 78 service repair manual, but it doesn't show anything. also, is there a way I can check the valve to see if its working correctly ?