I've got 2004 Armada LE with a hitch and the transmission oil temperature gauge.
I suppose it has a tow package.
Should it have the transmission oil cooler and if so where is it located?
If not should I install one like from Uhaul before towing 7000 lb boat?

All Armadas have two transmission oil coolere. One is in the radiator tank, and there is a air cooler located between the radiator and the A/C condenser, at the top on the passenger side.