The M-R-S A-100 is a four-wheel drive (4WD) tractor produced by M-R-S from 1962 to 1980. It was built in Flora, Mississippi, USA. The tractor is powered by a Cummins 7.6L 6-cylinder liquid-cooled diesel engine delivering 120 hp (claimed drawbar). It features a 4x4 4WD mechanical transmission with power four-wheel steering and an open operator station. The tractor has a wheelbase of 100 inches, height of 117 inches, and ground clearance of 17.5 inches. It rides on 23.1x26 tires front and rear.