This fuel cell tractor made by Allis Chalmers the mid-century, ran on propane.
During the mid-fifties, Allis Chalmers experimented with fuel cells to produce electricity and to power tractors. Propane was the main gas used for fuel in their fuel cell tractor which came out in 1959. The gases were carried in several cylinders housed beneath the rear axle and behind the driver's seat. The gas was fed through to the banks of fuel cells which filled most of the space normally occupied by an engine.
It weighed 5270 pounds and had 1008 individual fuel cells arranged in four main blocks. The current produced by the cells was used to power a 20hp electric motor which drove the tractor. Each fuel cell was about one quarter of an inch thick, 12 inches square, and produced approximately one volt of output to total about 15KW.
The speed was controlled by a single lever which governed the amount of current fed from the fuel cells to the electric motor. There was no reverse gear, but another lever was used to reverse the polarity of the current so the motor ran backwards.
In a demonstration, the tractor delivered 3000 lb of drawbar pull under test, and pulled a two-furrow plough in dry, hard soil. The tractor ran smooth and quiet, its waste gases were clean, it had no moving parts, and it was twice as efficient as other tractors during that time period.
This tractor is now exhibited in the Smithsonian.
Note that some of the above information was obtained from a 1983 Power Farming Magazine.