You're actually correct on this.....except for the stupid insults that aren't necessary.
I researched it a bit and Ford does not use the viscous coupling for AWD, they use a transfer case. It's different than the 4x4 transfer case but a transfer case nonetheless.
I can say from FIRST HAND EXPERIENCE that the AWD system in the Dodge Durango does use a viscous coupling and will experience trouble if the tires are not very closely matched. I've seen it happen.