So the end result I am searching for is, is my 2008 good to go? How would I know if it has a new style radiator? I am in Arkansas so we see many 100+ days in the summers and haul from time to time so bypass is not a great idea
Its up to you, according to what I've been tracking no 2008's have been confirmed. The 1 on the list was likely not SMOD related.
Here's the list:
http://www.thenewx.org/forum/showthread.php?t=62655
The general consensus is that fluid was changed in 2009 and a new radiator part number was also issued around that time. I've been on this board a few years and I have yet to see a definitive answer.
I've seen folks say they love the by-pass and others say it caused them issues. Those that experienced issues appeared to be less heat related and more how they used their truck (heavy towing or off roading, low speeds w/limited air flow, etc.)
The list I posted was my attempt to quantify much of the anecdotal responses on the site. The best I can tell, so far no member with a 2008 has posted with a SMOD issue.
Does this mean no 2008s have or will get SMOD? Who knows, the sample size here is relatively small and 2008s are still relatively new. People know its contamination of fluids that occurs due to an internal breakdown of the radiator. But what causes this failure is uncertain. Is it mileage, or environmental (salted roads), temperatures, etc? Hell there are plenty of late model Xterras w/hundreds of thousands of miles on them and no issues with the stock parts. What makes them so special? Couple that with the fact there's little confirmed evidence on part changes (though there is a general consensus on fluid swap and that a part change did happen at sometime) and I could see your worry about which year.
Nissan did issue an extended warranty on Xterras to cover this failure. Though I am unsure if it is transferable to a 2nd owner. The warranty covers all parts related to SMOD up to 80k for $0. After 80k - 100k deductibles come into play - starting at $1000 (the cost of a new radiator anyway and then some.)
My personal opinion for your situation - if you are covered by this extended SMOD warranty, continue with the sotck parts and monitor for any SMOD issues. If you are not covered, then I would either by-pass w/an extra transmission cooler and some sort of transmission temp gauge. OR preemptively replace the radiator setup.