The 12-20 started as the 10-20 with ignitors, but there's only one 10-20 left. The 12-20 started production in 1918 and went to 1924. In that time 7,282 units were made, but only 114 survived making it a sad 1.57% rate (the lowest of all oilpulls). The 12-20, according to Nebraska Tractor Test #10, was able to put out 26 HP on the belt & 15 on the drawbar while weighing 6,638 lbs. This was impressive for it being the smallest Rumely ever made! It had a two cylinder, kerosene burning, heavy duty, 6 inch bore, 8 inch stroke, engine running at 560 RPM. Other specs are available ON REQUEST. For more SN info on the 12-20, CLICK HERE.