1985 Ranger with 2.8l should have mechanical fuel pump on the side of the engine, so no in-tank fuel pumps, and no fuel Return lines
Look in the frame rail under drivers seat area for selector valve and fuel filter.
Adding it won't be very hard, universal valves will work fine.
They have 3 hook ups for hoses, 1 for each tank and then an OUT to engine fuel pump
Universal valves select front tank if no voltage(OFF) and Rear tank if they have 12volts(ON), so really just 1 wire is needed from the cab switch if you Ground the valve on the Frame Rail, which is what most are already set up for, they will only have 1 connection on them for the 12volts, metal of the valve needs to be bolted to the frame(ground)
Wiring for the Fuel Level for each tank is also fairly straight forward, if senders in the tanks are still working.
Coming from each fuel tank will be 2 wires, Yellow wire goes to the dash fuel gauge, other wire is the Ground for sender, and can be hooked to the Frame Rail.
Ford sometimes used Green wire on one tank and yellow on the other instead of 2 Yellows.
These should already run into the cab, but if not then you will need to run 2 wires into cab to the Tank selector switch on the dash.
Sometimes both wires from each tank ran into the cab and the 2 grounds were grounded to the cab body instead of Frame Rail, which is better since gauge is also grounded in the cab.
Then find the Yellow wire from the Fuel Gauge and run that to the Selector switch as well, the Yellow wire from the gauge will have 5volts from a power supply behind the dash, it is Pulsed 5 Volts so some meters will jump around if testing voltage on this wire.
Fuel level circuit
Dash 5v power supply----------Gauge------------Dash Switch------------------------------------Sender/float in tank---------Ground
At the dash switch you are just switching connections to senders
Ford Selector switch is just a toggle/rocker switch, switching contacts from one tank's sender to the other.
And will also have a 12volt contact to send 12volts to valve or 0 volts to valve
Also some have 1 connection for illumination and a Ground, this would be connected to Dash lighting wire
Unless you are planning a full restoration then using current valves and switches will be best bet.
I prefer having 1 inline filter on each tanks fuel line and then into the Valve and out to engine.
Normal setup just has 1 inline fuel filter that is on the OUT hose of the valve, which is fine.
My thinking is that if a filter does start to clog up I can switch to the other tank, that never happened, lol, but for $8 I figured why not.