Tri-ax, air up and air down. 1979, 21 foot box head-lift hoist. Runs and drives good, frame good front tires great, back tires need a few replaced some time. It has 4 new batteries. Cab is rusty but the frame is not therefore the price is very affordable. Haul grain, gravel, dirt, silage whatever. Lights, wiper, heater all work as they should. Mack engine , 5 speed, and mack rear-ends.