Allison Transmission Holdings Inc. is an American manufacturer of commercial duty automatic transmissions and hybrid propulsion systems. Allison products are specified by over 250 vehicle manufacturers and are used in many market sectors, including bus, refuse, fire, construction, distribution, military, and specialty applications. With headquarters in Indianapolis, Indiana, Allison Transmission has a presence in more than 150 countries and manufacturing facilities in Indianapolis, Chennai, India, and Szentgotthárd, Hungary. Wikipedia