how do you remove gas tank from 2005 astro. It is a plastic tank with shield.

There are no special tools needed. You need to unhook the filler and vent lines. Depending on the exact design, you may need to detach lines from the tank with it partially lowered, if they can not be detached at the filter or junction at the front of the tank. The connectors are all plastic, be careful not to break them. It is preferable to have the tank as near empty as possible when you do this. Use a floor jack to support and lower it.