Witness the biggest, most powerful diesels ever built – The Union Pacific 6900 Centennials. Developed especially for the Union Pacific, EMD's DD-40As filled the need for greater efficiency, ease of maintenance, speed, and power. Delivered in 1969 and named Centennials for the 100th anniversary of the first transcontinental railway, they were marvels of modern technology and performance. In this special release, you'll thrill to the sight of Centennials, or "Big Jacks," traveling across 5 different states, through all types of terrain. In 1986, after 17 years of amazing duty, the 6900s were retired. You won't see them in operation anymore, but this great video lets you enjoy the sights and sounds of Centennials in action again!