'57 was the first year for a new design of the speedo cable having differences at both ends from the '56 and earlier design. The '57, 58 and 59 years all probably use the exact same cable.
Nowadays, you need to be careful when ordering. The repro distributors are supplying one cable length of a specific design that will fit your car that also fit a variety of other makes, models and years.
Thus they will send you one that may be a lot longer than it needs to be. That can cause a problem.