they offer three sets of shocks, rancho5000 rancho 9000 and the bils.
the rancho 5000 and bilsteins are roughly equivalent 'stiffer off-road shocks'. bils are generally considered a little better quality shock, which is why they are more expensive.
the rancho 9000s are adjustable..meaning you can make them soft or stiff however you want.
the bils they sell don't exactly fit the 05+ x. the lower shock mount is missing a bushing that the OEM shocks come with. plus they're narrower than the OEM shocks are. nothing to really do about the busing, but you need to put washers on to make the shock fit on the bottom.