I have one of these engines--I believe they were given away as premiums from Reader's Digest at one point, and may have been given out by other companies as well. They don't look too bad, and appear to be of accurate scale size. In fact, I believe the picture on the box is of an old Atlas release, and the shell on the toy may have been molded directly from it.
The couplers are Rapido-shaped, but mounted solidly to the body, so they don't move at all. However, they are a separate piece from the body, so removing them and inserting a "real" coupler pocket and coupler should be do-able.
The wheels are mounted toy-car-style, with a clip holding the center of the axle. They'll roll, and sit on a standard piece of N-scale track (and have reasonable flange height). However, I don't think the wheel profile would serve to keep it on the rails as part of a train.
