Funny, that fully reminds me of back in 2007 when Ford was going back & forth about whether "Mercon V" fluid was a compatible replacement for "Mercon".
Initially Ford insisted they were incompatible (warranties would also be voided if you used one fluid where the other was spec'ed), but then later they would say Mercon V was backward-compatible with Mercon. They then said not compatible one more time before finally settling on "compatible" and then yanking the licensing for the Mercon name (perhaps this was the same type of conflicting info across the various Ford sites like was on that forum link). Meanwhile about that same time some people's M5OD transmissions started shifting like crap because the Merc V fluid additives apparently made it too slippery for the synchros to function correctly (they should've stuck with their initial stance).
I will add however, in this particular instance involving a transfer case WITHOUT an electric spin-up clutch (all manual-shift cases, all 2001 & up cases), almost any ATF fluid would likely be fine (inc. Mercon V), but I absolutely would not recommend putting Merc V fluid into a manual transmission that does not explicitly call for it, nor in a t-case that has a spin-up clutch).
Like adsm said, easiest to just stick with fluids having the original formulation.
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