Well, nice model but I do not like the front end, I picked up on the coupler straight away.
As for the noise of a "D", well having both fired and driven these locos, the noise I can hear now, when they are at work with a train behind them, the noise is two LOUD beats and two softer beats and did you know that a Super "D" was prone to "running" away when moving around either a yard or a shed, the water used to build up and when you opened the regulator and closed it the loco would keep going. Many a driver shook up by them doing this.