Volume 3 of the history of Commonwealth Engineering picks up the story where volume 2 left off. The takeover of rival firm A. E. Goodwin allowed Comeng to enter the lucrative and very successful business of building Alco-powered diesel-electric locomotives, for the growing iron ore mines in Australia's northwest. The company's long-established business of building buses and other road transport vehicles continued, as did the arm of Comeng that supplied curtain walling for the high rise buildings around Australia. The company was now the largest rolling stock manufacturer in the Southern Hemisphere.