The "number board" a simple part of a locomotive, yet important in many ways. This specific number (4035) belongs to a locomotive in the CSXT fleet. Providing similar info as a social security number does for us, it gives a history on the engine. So... this number informs that this locomotive is a rebuilt SD40-2, now becoming a SD40-3. It was originally built in July of 1979 for the Seaboard Coast Line Railroad then after a merger, belonging to the Seaboard System Railroad and finally CSX Transportation. During the stretch of years, it was numbered (8062). It produces 3,000 horses and 130,000 lb of tractive effort. Also maintenance history and inspections are cataloged under its number... No matter if just the location of a locomotive is needed, an emergency situation, or if a full history report is required, all the information is tied to the number board. Photo taken with permission.