Leaky Gas Tank

[Turbo85GMC]

While investigating the gas odor coming from my truck, I found that the plastic rock-shield had collected a ton of water and sand. That ended up rusing out the brackets that hold the tank as well as the rear strap. The bottom of the tank is all rusty and wet with gas, it obviously has a couple pinhole leaks. Do I need to take the bed off to replace the tank and support brackets, or can I do it from underneath? Also, does anyonw know where I can find the brackets for sale? I tried looking in the Chevy Duty and LMC catalogs but couldn't find them. Are the gas fumes affecting my vision?

EDIT: I found this picture on some guy's web site. This is one of the brackets that I'm looking for.