I checked the ground wire right in front of the gas tank, pulled it off, cleaned it, and put it back on. It didn't fix my problem. I tried to drop my tank but the bolts are being stubborn so I'm calling Ground Up for a new tank mounting kit tonight. Do you guys think it's the ground wire on the sending unit side that's causing this? As soon as I turn on the key, the needle goes about 1 1/2 inches past full. Help.

What does the gage read if you ground the sender wire? Should move the gage to empty.

As John said, What does the gage read if you ground the sender wire? Should move the gage to empty. Do this first, it will tell you if the problems at the tank or somewhere else. To do a test go here
http://www.chevelles.com/forums/showthread.php?t=93013
If the gauge move to empty then you problems at the tank, if no movement its before the connector that you tested at.