Eric M, that was a great video and it explained it in a way I can comprehend, thanks for sending it!!!! However, one last question, is the following statement correct; the reason 4 H should not be use on pavement is because the rear differential is locked, which will not allow the wheels to spin at different speeds for turning, however if the truck is driven in a straight line, no harm, no foul? Again many many thanks!
Whether you are in 2wd or 4wd- having the rear axle locked will make turning on dry just that much harder as you are now eliminating the differential action in the rear axle. Don't lock the rear axle unless you are doing burnouts, driving in 100% loose material (mud snow gravel sand), or you are rock crawling at slow speeds.
4H can be used on dry roads if the Tcase has a clutch or differential in it to allow front and rear axles to turn at different rates in turns. 4WD Auto is just that- running in 4H with either a clutch or an actual differential in the Tcase allowing differential speeds between the front and rear axles.
Gen 1 trucks are the ones that should only be driven in a stright line if it's on a dry road. It's not the best thing to do on a Gen 2 or 3 truck for the ultimate longevity of the drivetrain, but they should be able to handle dry roads in 4WD Auto due to the Tcase allowing differential speeds between the front and rear axles.