I got a new sending unit in my 67 because the old one was trash. The gasket that came with the new sending unit is too big and doesn't fit in the Chanel. The gasket leaks and gas leaks out. Does any one have any ideas?

 

I'd go to a well stocked parts store and buy a roll of gasket material. Use a sharp razor knife and make your own gasket. Its easy and only takes a few minutes. Don't blob on silicone to seal it up, use it sparingly.