Fuel Pump Whistle

I'm looking at purchasing a 2000 Yukon XL with a 5.3. I commented on the whistle that i heard coming from the rear of the truck and was told that it was normal for the fuel pump to make that sort of noise. Has anyone else noticed a similar noise? Could it be an exhaust leak instead? Or is the pump in need or replacement?

Thanks!

its normal for the fuel pump wine...