gas gauge

I recently bought a 1987 Ford Ranger 4x4 ex cab with a 2.9 liter motor. The gas gauge does not work. Is the a list of things I need to check before I replace it? Do I need to drop the tank to replace it? How much money am I looking at to replace it?

one thing you could do is just go by the miles, figure if its a 15 gal tank, you'd probably get about 200 miles. if you really want it fixed, you could drop the tank, and replace the floater inside the tank.

i have an 87 ranger xlt 4x4 too.. extended cab.. and i have the same problem.. i bought it from my uncle and he said they cut a hole in the bed and replaced everything on the tank.. so idk if that include the floater or not.. i would like a working gas gauge though so i don't ever have to worry about running out. and calculating gas is easy but a pain i just want to fill it when it gets low.. is the floater the only thing that it could be?