If you're going to use it, the amp draw is all that would make a difference. Thats plenty for a newer trolley or starter set loco... except there is no throttle.
I'm running a trolley with a 70s Radio Shack 2.5a 12vdc with 6 4a diodes to slow the speed to about 8.5v. Off or on. A three position switch = a three speed. I have 9 speeds on a 4amp12v RS unit too.
Look at the cord and insulation etc.. If the breaker isn't just a fuse, test it. (Cant tell).
If you put a 2amp draw on it, then it should level out to just above12vdc. At the 2.5 amp max at least 12v should be there.
You can get 2.5a 12v out of a wall wart today, But I like the old boxes 
