In my opinion these are wonderful engines that run and look great. 313's were made from 1955 through 1957. They have traction tires, red glowing smoke and most importantly a 4 position reverse unit in the tender. They do not have an air chime whistle so they can be run with any power supply (not just a pure sine wave output) without the tender whistle constantly sounding.
There are several variations, the most significant being large or small motor. The small motor has a 1/2" long rotor, the large is 3/4" long.
Enjoy your engine!