After looking thru the 04 Armada sales brochure and accessories brochure, there was only one tow package (Big Tow, std LE, opt SE) offered with a dealer installed motorized (Titan) mirrors available. Only one hitch; class III/IV was offered by Nissan in 04, you could have the hitch dealer installed on SE Armadas(I think 6,200lbs)w/o Big Tow and miss all the other good stuff that comes w the (9,100 lbs) package. Maybe it is different for 05, I do not think you would want to exceed the realistic tow load of 8k anyway (I have). MERRY XMAS!!!!
Now to the point. The real difference in the tow ratings is that the offroad models have the Rancho shocks which lowers the tow rating to 6100lbs. (warranty issues?)
If you get the offroad package with the big tow package they delete the Rancho shocks to maintain the higher tow rating.
So when I went shoping I got the SE Offroad 4x4 and put the hitch on myself. I drove all the 4x4 models and in my opinion the combination of the Rancho shocks and the bfgoodrich 17" tires provided the best ride.
I don't have the trans temp gauge, but I will never pull more than 5000 lbs.
The factory installed big tow package includes the auto leveling feature which consist of large air shocks on the rear with a air compressor and control circuits. This allows the tongue weight of 910 lbs, and 9100 lbs towing capacity.