Being the pre-production model of the Willys MB, better known as the »jeep«, the Willys MA differed from its successor mainly by the deeper body side cut-outs, the single top bow/hand rail, the slightly lower windscreen and the »column gear shift«.

Some 1,500 samples were produced in the summer of 1941 of which the vast majority were provided to the QMC for Foreign Aid, the main recipient being the Soviet Union in the fall of 1941.

Together with the slightly smaller Bantam 40BRC, the first MAs are reported to have participated at the successful Russian winter counter-attack of 1941 in its role as command and reconnaissance car.