N 4-6-6-4 with DCC & Sound, UP #3933

N 4-6-6-4 with DCC & Sound, UP #3933 Union Pacific In the spring of 1941 UP locomotive designers began working on a locomotive to team up with the new 4-8-8-4 Big Boy's then under construction at Alco. The Big Boy's were designed to pull heavy freights up the Wasatch Range in Utah to the division point at Green River, WY. What was needed was a locomotive to take over at that point that could speed the freights eastward across the Wyoming Division. Building on their experience with the original CSA 4-6-6-4 Challengers UP and Alco's designers developed a newer and better Challenger type locomotive. The result was a group of 65 4-6-6-4 Challenger built in three separate groups during World War II.  ROAD NUMBER SPECIFIC FEATURES:  #3985 Modern Excursion version Oil Burner Era 1980's - 2000's #3933 Coal Burner Dual smoke stack Tender bunker coal extensions Era 1940's - 1959 #3967 Coal Burner Dual smoke stack Smoke Lifters Era 1940's - 1959 #3997 Coal Burner Dual smoke stack T