All this rock crawling talk, back to your initial comment about 4-lo.....yeah with the auto tranny and full time 4WD with the CDL switch, it's tempting to stay in 4-hi. But your tranny & torque converter will roast and so will your engine eventually. So, my suggestion is to use the gearing and...
^^^^^This plus marco is comparing apples to oranges. An armored up 80 is almost twice the weight of most jeeps. An old boss's of mine comment: "I hate my jeep. I drive it for a day and work on it all week to get it ready for next weekend."