I have an '06 Xterra X model and I love it. The reason for the model I chose instead of the OR was the availability of an OR 6spd. Just a serious pain to find at the time I was looking. Also, for the money I've spent upgrading my X I paid about the same or less than a stock OR model depending on the dealer extras. As well, all the '05 on Xterra's have ABLS which help move you along when a tire slips or is lifted off the ground. Mind you not quite as nice as a locker, but better than pure open diffs. If all else fails I have a winch and I'm not afraid to use it
Oh, oh, and there is now an ARB locker available for the m226 diff (6spd's and OR's) that I have. So, I'd still be less expensive even after having one of those installed that an OR model :Wow1: (most OR models on the lots were grossly overspeced with extras as well)
Sorry for the lengthly explanation, but you asked why :elkgrin: