Classic Machines TractorsThe Allis-Chalmers HD-20, last of A-C’s GM-powered CrawlersContractor MagazineJune 19, 2019July 8, 2019 by Contractor MagazineJune 19, 2019July 8, 2019 A big tractor in its day, The Allis-Chalmers HD-20 was another part of the power struggle that took place between Allis-Chalmers and International-Harvester during the
