Replacing your trailer's 120V power cord is an easy update that will improve the safety and reliability of your power supply.
Most vintage trailers use a hard wired (permanently attached) power cord to bring 120V AC power into the trailer. The three standards are 15A, 30A and 50A. 50A is not necessary for vintage travel trailers except in very rare situations. 15A is adequate for small trailers without air conditioners. 30A is the majority standard and the best bet in most cases because it can provide adequate power for almost anything you plan to do now or in the future, and it is available at almost all RV campgrounds with power.
When you replace your cord, we highly recommend selecting a flexible rugged cord like ours, with a molded male end and heavy gauge 10/3 AWG wires. Make sure you have enough length to stretch all the way to your trailer's breaker box without interruption. And then to a campground box safely away from the rear end of your trailer. Ours is 30 feet long so that you can make the full run and cut to your desired length.