clear through physical examination that it is a rebuild. Once so rebuilt, the locomotive enters the owner's fleet as if it were a true SD40-2, arguably the most versatile and reliable diesel-electric locomotive of its time, if not all-time. Although not as popular as the SD40-2 rebuilds, GP40s, GP39/SD39s and GP38/SD38s have also been rebuilt to the equivalent of GP40-2s, GP39-2/SD39-2s and GP38-2/SD38-2s, so significant were the reliability and serviceability advantages of the Dash 2 line. Subsequent models Models subsequent to the Dash 2 line, for example SD50, SD60 and SD70, et al., incorporated Dash 2 improvements at the outset. In this context, the model suffix -2 is only applicable to the 40 Series, although -2 has been applied to certain variations of the later models. References Dash 2 Diesel-electric locomotives of the United States Railway locomotives introduced in 1972