4-wheel drive question 4-you guys?

this is a normal condition on some vehicles. the 4LO setting provides greater torque output to the wheels, through gear reduction in the transfer case. the vehicle will lunge forward in drive and reverse when in 4LO. has this been doing this the entire time you've had the vehicle??

the only thing i can think of, other than normal condition, is the transfer case vacuum switch might be faulty, and allowing the vacuum to bleed off, thereby not allowing the power brakes to accumulate the needed vacuum to operate the brakes, but that theory is a thin limb

I'm not sure why it stops worse in 4 low than 4 high, the only difference should be the final gear ratio. Low is better for towing, high would be like normal driving. But when your truck is not pulling a trailer it will mainly use front brakes to stop. The average distribution is like 65% front and 35% rear. So instead of checking your rears, you may need brake pads, or something up front.

I have a similar problem with my 98 Durango. My rear wheel hubs need replacing and I do have 150,000 miles on it. So I would quess that if you have over 100,000 miles, you might want to have someone look at your hubs. I did my front already and they were rusted bad. By the way, The hubs have bearings in them and they will wear out in time, Good Luck!