QUOTE: Originally posted by icmr It is one of UP's early Challengers. It was built in 1937. It is a Class CSA-2 bulit by ALCO for passenger service on the UP and converted to burn oil when delivered in 1937. The one in the picture was originaly 3939 until 1944 when it was renumbered to 3839. It was 110'-7" long weighed in at 876,000 lbs with tender. Now this is just a guess from what you gave us to work with. ICMR Happy Railroading.[swg][swg]