That thread, like many on a number of Xterra boards, goes on and on about what is correct but in the end still fails to give you an answer to the original question.
I am far from an expert and only responded with stuff that I have actually done to my truck. You can check the Bilstein site
HERE and see that they recommend the same part # that I did except the front is with the stock dampening (H2 instead of H0). H0 is the 20% stiffer that you asked for and will come up as ?Nissan Front?. The # I gave you for the rear will come up as ?Toyota T100 RWD? but it is correct. If you look at the ?notes? for the Xterra recommendations you will see that it says that you use the ?Yellow shock (Bilstein HD), zinc plated shocks are not available for this application?.
So the #?s I gave you are for the 20% stiffer, yellow Bilstein shock with the blue boot that I?ve been running on my lifted ?01 Xterra with Shrock bumpers and a winch for more than 4 years. I bought a set with my lift kit from SLR and bought a set from Summit. At that time they were sold to me as 5100?s. I would rather not get into a debate over on XF (or here) on what they really are because, to tell the truth, I don?t give a shit if they are 5100s or HDs. They work great on my truck brother. I hope that answers your question and therefore helps you out.
Old pictures when my lift was first put on.