I bet you need a new sending unit... that retainer ring area looks pretty rusty. Did you use a flash light to look inside? I have yet to see a gas tank that didn't need attention inside, not that there aren't any out there. If you need any parts going back together try AutoKrafters, they have what you need . Was the car sitting before you started the project? Why did you start the project anyway? http://www.autokrafters.com/
ok so im putting it back together tommarow and i was wondering if it was a problem that there wont be fuel in the fuel lines when i try to start it up, how will that work. will the pump just suck air until it gets gas and i will have to crank it for extra time until i get gas ?
That depends, if the car was previously running from the gas tank the last time it ran, then it will probably never miss a beat when you put the new tank in, since there is still gas in the line and carb. If the system is totally dry, you may have to put a little gas down the carb a few times and do some cranking to get gas sucked up there. Just be careful not to crank too much and overheat your starter. I have a '72 and '73 tank that are literally spotless shiny metal inside. My '69.5 tank is also spotless inside and out. The '73 tank is solid as a rock, and has absolutely no rust on it anywhere, but strangely it developed a small pinhole in the bottom anyways. I have no idea why. Took it to work and my boss welded it up.