I have used differential for lock for years for that quick bit of traction to get thru a slick spot, as previously said, when going straight you can engage it just before you hit the "mud" to prevent slipping in the first place, but just remember to let off of the lock, as soon as no longer needed and before any turning is needed. Another thing you can do when spinning starts with one wheel, and the other rear wheel is stationary, you can tap lightly the split brake of the wheel that is spinning. This places pressure on the spinning wheel brake, and will make the other wheel start to move foward through the action of the spyder gears in the differential. Dont try to lock the spinning wheel, just put enough pressure on the brake to start the other wheel moving foward, feather as neccessary to keep moving foward. This is the principal that some trucks and cars use to prevent wheelspin thru dynamic braking of the spinning wheel under computer control. You can also use this function to "screw or turn" you out of a slick spot onto drier ground. If slewing a foot or two in the proper direction will get the tires onto better ground. You can use this brake steering as you steer the front wheels also. By the way the Differential Lock will have no effect on your front differential, just the rear,
James K0UA