Drivers seat

You didn't tell us the type of vehicle you have, but as a general rule, anything from the same generation as your vehicle will fit (just go to your vehicle's Wikipedia page to see what years are for that generation.) In addition to your specific model you may have one or more sister models that will also fit. (Example, A Ford Taurus is basically the same thing as a Mercury Sable.) If you go to any salvage yard or auto part dismantler, they usually have an interchange guide and can tell you if they have a compatible seat in stock, and if not can even tell you who in the area does.