RE: You gas gauge's secret
I knew this, but my wife didn't. It was pretty funny, she had just gotten a new car and couldn't figure it out and then I told her to look at her dash. She felt dumb, but obviously no reason to be.
For GM, the 1956 model year is when the driver's side taillight was hinged to allow access to the fuel filler. Many 56 GM owners loved to play games with the young gas station attendants while enticing them to "find the hidden gas cap".