flipping it back in 2WD after launch has been done has been know to strip out the hubs over a period of time. I will not hurt to leave them in 4HI with your hubs in the "Automatic" position because they are designed to slip a little. This is why they do not break the front end parts. The older trucks were the ones you don't drive on asphalt with. when launching your first time in 4HI you will have to hold on that brake really hard but make sure you roll a few feet at idle to make sure they are engaged if not they might engage right after you take off and then your back shaft is moving faster then your front and might strip your hubs and make some god awfull noises. OH YEA make sure you are resting your head in the head rest when you do it. It could hurt. Make sure your dog is not in the bed of your truck