Because the HRTC and 4.11 TLC axles will give him the high range equiv. of ~3.55 diffs, even with the GM 4 cyl that is pretty tall gearing with (presumably) 32" tires

4.11 diffs give him the same reduction +- as a HRTC alone would. (4.09 vs 4.10)

4.11s will give him ~2722rpm at 55mph
4.7" "" " 3121rpm at 55mph

4.11 + HRTC= 2059@55mph


IMHO the 4.11 diffs alone are the solution he is looking for unless he finds he needs to go to a lower 4.56 or 4.88 diff ratio because of power concerns on road.

http://www.izook.com/gearcalc.htm