fuel tank replacement? on 1999 Chevrolet Suburban 1500

What is the cost of a fuel tank replacement. I went to my truck and I notice the smell of gas and didn't notice anything, but checked again in the morning and notice a quarter size drip on the ground. Then two days later as I let my truck sit, I notice it doubled in size. I then notice the leak was dripping from the gas tank guard and seem like it was coming from the top>

You may or may not need a new fuel tank. But first, drop the tank and check the fuel tank module on top where the fuel lines hook to. I would be more likely to bet that one of the plastic connectors is cracked and you just need a tank module (still around $300-$400, at least in CA). I haven't replaced too many tanks, but lots and lots of modules.