Answer to the last question about locking differentials. Keep the original, it is made to be the way they are. A couple of years ago, a member on this forum called Teddan tried to put locking differentials in the front axle. It did not work, the differentials broke. If you are unlucky, the axles may break down and they are not easy to find or cheap. So my advice, take it or leave it, stick to the original. Maybe some other members have other experience.