The Nacionales de México class G-030 consisted of 20 three-foot gauge Consolidations delivered by Baldwin in 1921. The outside frames were designed in such a way that a later conversion to standard gauge would have been possible. They were fired with oil and were designed for lines with gradients of up to 4.5 percent and curve radii of up to 21 degrees (85 meters).
In reality, however, there were only a few modifications that were carried out by the NdeM shortly after delivery. These affected, for example, the blastpipe, the position of the air pump and the fire door. Eight more followed in 1924, which had a larger firebox and were designated class G-033. They became the standard freight locomotive in rural areas and survived until the late 1960s. 