My rear ball diff failed on me last sunday while batting a Durango DEX410, embarrassingly. I really believed I could have at least kept up with the DEX410 if my diffs were working. I am now installing gear diffs in my MID. I used Xray TC 300,000 gear diff oil filled only half. I did this to make sure the diff wont unload too easily and also the pressure in the casing will not be too high and cause the oil to leak out. I tried this and the diff is quite hard but still movable. The silicone oil should ensure that the setting remains constant and wont loosen up. For the front gear diff I used RIDE TC putty, to make the front diff almost like a spool, just the way I like the car to handle, very stable.
I will let you know how it goes. I hope the large bevel gear will not separate out from the shaft, or I would have to take the car apart yet again...
