A 2X4 uses one differential.
A 4X4 uses two differentials.
A 6X6 uses three differentials.
I suppose you could label it a 4X6, but technically speaking, a "Dual Rear Wheel" is a composite assembly combining two rims into one, so you still only have two differentials turning a total of four hub/wheel assemblies.
Army "Deuce 'n a Half" trucks and 5-Ton Trucks are good examples of true 6X6's: three seperate axles with three seperate differentials.
HOBART Champion 10,000
HTP MIG 2400 c RSG250 Spool Gun
HTP Invertig 201 AC/DC - WANTED!!
Lincoln PrecisionTIG 185
Smith O/A Rig
Clark 1/2" Floor Drill Press
Clark 6" Bench Grinder
DeWalt 4.5" Grinder
DeWalt 4.5" Grinder #2
DeWalt 4.5" Grinder #3
B&D 18V 3/8" Drill
B&D 18V 3/8" Impact Driver
Now in order to kill the enemy, our men must be roused to anger; that there may be advantage from defeating the enemy, they must have their rewards. ~Sun Tzu in "The Art of War"