Indeed they don't have a diff as such, they do have a limited slip in the drive train, so basically the left 3 wheels can slip different to the right 3, that is why when flying down the motorway the truck tends to go to the left, then the right and so on (but only slightly)
99.9% of problems are with the lack of proper maintenance, tyre wear can be reduced if the pressures are checked every time, and oils checked and maintained. My friend has one in Leeds, he drives it everywhere and has no problem, last year he came to war and peace show in Kent, driving the stolly and towing a land rover, then after the show drove it home! The only problem he had, was the (non original) flashing beacon fall off!
They are awesome off road.
I could tell you lots about them and go on and on but that would be for a different section!