gas tank Q

So, what is a driver-quality used Mustang II gastank worth?

I have a spare one, and the guy I just bought my King Cobra from needs one. He's willing to put the value of the tank towards what I still owe on the car, but I can't find any tanks on Ebay to help us figure out what its worth.

Just looking for a ballpark value...

Thanks.

We ended up working it out at $150 credit on my "New" King Cobra, and he'll give me the sending unit back when he pulls it out.