Classic Machines TractorsClassic Machines: The Allis-Chalmers HD-20 tractorCharles FairbairnMarch 23, 2016June 29, 2018 by Charles FairbairnMarch 23, 2016June 29, 2018 In production for just three years, the HD-20 was the stepping stone between the powerful HD-19 and the very successful HD-21. RICHARD CAMPBELL delves into
