Gas tank trouble

The gas guage on my son’s f-150 dual tanks do not work.

They say we’ll have to drop them to repair.

What actually will need to be replaced and can we do it ourselves?

The gauge doesn’t work at all?

Do the two tanks drain together (no switch over)?

Before dropping the tanks ensure the wiring circuit is good and there is a good ground connection.

It is possible the sending unit may be faulty. In the tank?

The reason the tanks need to be dropped is to get access to the senders in to gas tanks. But, for both to be out, I question the immediate need to drop them. For both senders to be bad at the same time is unusual. The usual culprit is the three-way tank switch or a wiring problem under the dash. These need to be ruled out before spending money to drop the tanks. BTW, electrical problems like this can be hard to find, and cost a lot just in the labor time.

No, the gauge doesn’t work.
There is a switch, and when the switch is flipped there’s movement.
One solution I came up with was to fill the front all the way, and put about $20 in the back.
When the front runs out, he can switch to the back.
That way, writing down the mileage we’ll know approximately how far he can go.