So I was just chatting up a Jeep engineer about the driveline in the Cherokee with the active drive II and about how you stuff a low range into a transverse engine fwd based unibody. Answere: 3 different reduction gearsets.
1. one right after the PTU (power takeoff unit) that send power to the rear wheels (thats the main one)
2. one in the rear differentials (just before it)
3. one in the front differential (same story)
the trailhawk has 3(!) "low range" gear sets!
Which explains how you can get a 56:1 crawl ratio. Which I can tell you...is a LOT!
For your troubles, have a pic.