I have somewhere near 1/4''to 1/2" of tarnish (tar like substance) from gas that sat in there a long time. This is the only thing I need for my 79 and it'll be on the road. Please help!... Thanks

 

Try a junk yard and pull one out and clean it up.

 

If your tank doesn't have any holes or anything, it can simply be cleaned. Either by a local gas tank/radiator shop or by yourself. Do a search on POR-15, it's a product used to clean gunk out of gas tanks. This page will show you tank differnces that you don't really need to know, but it's interesting to see the tanks... Also, at the bottom there's a link to POR-15 instructions

http://intertron.com/ron/tank.html

Jon