The fuel tank filler tubes get rusty and nasty over time. Replace yours and make sure you don't experience problems down the road. Danchuk # 12644 is the upper portion of the assembly which will work on any 1957 classic Chevy Nomad and wagon, except 9 passenger models. Photo is of Danchuk # 12641 which looks similar.
Danchuk has the largest selection of quality 55, 56, 57 parts for your classic Chevy project.