My best friend from HighSchool is an engineer there. He was on the launch in 2003-2005. He still knows guys in the Titan/Armada Platform Engineering Group.
I also found out that another change to the diff. part numbers that I referenced above is that the 05' has a 600N pull out requirement, not the 1000N requirement that are on the newer diffs.
Nissian and Dana are still looking for 2006 or newer Titans that have had the pull out issue. There are some reports of the axle pull out even after the change, but they said it dropped dramatically after the change.
As for someone buying the old version to "modify / repair". It's a lost cause in my opinion. I found a new diff on ebay for $500 (new part number). This is an 05 diff from an Armada. Armada's always got the fixes prior to Titans for some reason.
eBay Motors: Nissan Titan,Armada front Differential 2004-08 clean. (item 270335589308 end time Feb-24-09 16:23:28 PST)