Another option is to use cutting brakes as a cheap traction tool. Say you have a cutting brake at each rear wheel, but you do not have a locking differential. You could be driving up a hill and one rear and one front wheel start to spin until you stop moving forward. By applying the cutting brake to the spinning wheel, the open differential will send power to the other wheel, and if it has traction it will begin pulling you up the hill. This is sort of a poor man's traction control.