Do the FE and FG have the same travel in the suspension on the front axle?
Close enough to the same.
I dont see where this would necessitate a cab lift or changing anything on the rear of the truck.
There is no cab lift either. The cab maintains the same relationship to the chassis on both trucks. Suspension is setup on the FG so that the diff just clears the front of the engine. (a warning there if you go playing with bump stops).
Have a look at the FE front end (sorry don't have a pic on me right now but it would be easy enough to get one) . They run a beam front end so the wheels can sit a lot closer to the cab than they can if they had a diff.
As for the Dakar Truck photo
>>> it's running big singles. Look at a the difference between the 2wd and 4wd MAN TGMs below running approximately the same size wheels. See the relationship between the top of the wheel and the front steps in each photo. Also note the special mudguard they made up on the red 4wd to fill in the gap so it doesn't look so high.
The difference isn't quite as pronounced on the MAN compared to the FG as they run a very shallow diff ( OT but if you're interested >>
http://www.man.com.au/manau/assets/images/gallery/trucks/tgm/On Call Excavations 009.jpg) so they probably don't need to lift as high as if the diff was the same style as the FG but you should get the idea.. ..BTW MAN do a sort of suspension lift on the rear of the 4wd so as to retain the straight chassis. .