Instead of a single 50-amp breaker, the protection for the electrical system would be distributed through:
* Individual fuses: A 1962 Thunderbird would have a fuse box (likely under the dash) containing numerous fuses of varying amperages protecting different circuits (headlights, taillights, wipers, etc.). A problem would be indicated by a blown fuse.
* The main power source: The alternator and battery provide the overall power, but any significant overload would likely manifest as a blown fuse or damaged wiring, rather than tripping a single large breaker.
If you're having electrical problems, you should check the fuse box first. If fuses are blowing repeatedly, there's a short circuit somewhere in the wiring that needs professional attention. A mechanic specializing in classic cars would be best equipped to diagnose and repair any electrical issues.