The Athearn ATHG27320 is a high - quality HO scale model of the SD90MAC - H Phase I UP Union Pacific locomotive #8503. It comes equipped with DCC and Sound Tsunami2 for an immersive experience. The UP series: #8503 and #8500 were originally #8203 and #8160. Some models like #8509, #8512, and #8520 have unique fuel - tank features. Union Pacific was the sole buyer of the SD90MAC - H. The 8500 series represents the second and third orders delivered between 1997 - 1999. The SD90MAC - H locomotive features a brand - new model previously only in brass. It's fully - assembled, DCC - ready with Quick Plug™ technology and a 21 - pin NEM connector. The paint schemes are accurate, and it's scaled from real prototypes. It has many detailed features like coupler cut levers, rubber MU hoses, and a full cab interior. The Genesis 2.0 version has etched walkway steps, illuminated number and ground lights, and dual Sugarcube speakers for sound models. Sound - equipped models have an onboard DCC decoder with SoundTraxx Tsunami2 sound, operating in both DC and DCC. The prototype SD90MAC - H Phase 1 had a unique sloped hood due to engine cooling needs, and only 22 were made for Union Pacific, all scrapped by 2009. This Athearn model offers cutting - edge details and great pulling power with its heavy die - cast frame.

Using this Athearn HO scale SD90MAC - H locomotive is a breeze. First, if you're using a DCC system, connect it properly using the Quick Plug™ and 21 - pin NEM connector. For DC operation, just connect it to your DC power source. The locomotive is fully assembled and ready to run right out of the box. When it comes to sound, the dual Sugarcube speakers will give you great audio quality. Whether in DC or DCC mode, you'll enjoy realistic engine, horn, and bell sounds. For storage, the packaging is designed to hold the model securely. As for maintenance, keep it clean from dust and debris. You can use a soft brush to clean the wheels and other parts. Make sure to check the electrical connections periodically to ensure reliable current flow. If you notice any issues with the sound or movement, refer to the DCC decoder manual. And remember, it's best to operate it on clean and well - maintained track to keep it running smoothly and quietly.