I just replaced the transfer switch in my 280. This is the new switch.
I couldn't buy just the switch, had to by box and delay timer as a unit. Your power cord, Romax cable from the generator and Romax cable to the coach will all go to the box and connect to the switch. The old delay was a resister about the size of an ice cube but the new one is a solid state printed circuit board at the left side of the box in the picture.
Like JD said change over is automatic and there is a 30 second delay after the generator starts.