Well I took a chance drove to the next state over and picked the differential up. It bolted right up and switches between 2 and 4 wheel drives great. I cant recall even trying the 4 wheel drive on the leaking diff since we have only had the rig 3 weeks. Tonight when I went for a drive and it was in 4 hi it had a noticeable humm when getting to about 25mph, if you take it out of 4hi it goes right away.. Is this normal to have some driving noise from the front when engaged or did I waste a ton of time and get a bad unit??