2000 Chevy Blazer Fuel pump

My blazer has not been having any really noticable problems except my wife says she has heard a wine like a bad belt sometimes in the mournings. The gas gage has been broken for about 5 years. Just yesterday I was driving and the car seemed to sputter just for a second then died on me. I turned it on one more time and drove about 100 yards and it died on me for good. We had it towed to a local mechanic. He said that it is the fuel pump that needs replacing. I think he is right, but he said that he needs to replace the entire fuel tank. I know that I have to drop the tank to get to the pump. But is there any reason I would need to replace the whole tank? Or can I just replace the faulty fuel pump?