I used the diff lock with the one wway in front. After several days there was a lot of slop in the rear end. Upon inspection the soft alloy groove for the locking pin had worn so that there was about 10 degrees of rotational play, and the pinwas bent from the torque so that it couldn't be removed without considerable effort to straighten it. I don't recommend it.
And on anything less than high traction, the rear end breaks away without warning when power is applied (too vigorously). jack