This chart shows the production years and horsepower of the Allis-Chalmers letter series tractors. Thanks to Ed Kubris for providing this chart.©2000-2021 - TractorData.com™. Notice: Every attempt is made to ensure the data listed is accurate. However, differences between sources, incomplete listings, errors, and data entry mistakes do occur. Consult official literature from the manufacturer before attempting any service or repair.