Make sure you inspect the tank really well while you have it out. If it's full of rust or there looks like there may be spots on the bottom that could rust through and leak, you might want to consider replacing it.

I bought mine from a place called Ponderosa Mustang. It was $130 which included shipping and a new sender unit & gasket. Also, it's 16-gallon instead of 14. It's a Mustang tank but drops right in and all the holes line up.

Drawbacks are...you need to braze a nipple on the top near the filler tube for the vent hose. Have a muffler shop do it if you don't have the equipment. Also, the filler tube is in the center and points straight up instead of slanted from off-center. A lot of people use this opportunity to bring the filler tube inside the trunk. It's much easier to fill and secured. Here's a photo of mine:

http://www.redfalken.com/forum/filler.jpg

Just something to think about. You can buy kits to remove the rust and coat the tank but it's almost as expensive as just buying a new one.