Photo-etched on ultra-thin brass, parts feature a near scale diamond pattern on treadplate and exact scale hole layout on steps. Parts are an exact drop-in fit for models listed. For Athearn SD40-2 (Pre 2007 Releases). In late 2007 Athearn redesigned the SD40-2 from the old Blue Box version to an improved one with individual noses. This set is for the older shell with the molded in place nose. Use Set 2036 for the new versions.