Just fitted a set of these to the disco, it is sitting much leveler now with a boot full (was sitting so low at the back the top of the tyre was up under the arch, now there is about 4" clear) Not tried it on the road yet.
I bought them from Island 4X4 in the end. Kit comes complete with everything you need to fit and use manually (pump up on tyre type valves not built in compressor) all for