I have a 2006 1500 4WD. When running my truck in 4-hi (over 45 mph or so), there is a strange whine that was not there the last time I used it. Heavy rain this morning had me use it on my commute. The 4wd works, but when stepping on the gas, the whine is louder. It is not a constant whine, but pulsates (pulsating is not rythmatic, but random). Whine goes away when taking foot off gas, returns when giving gas.

I've had this truck in the shop twice, has 18k miles on it. Rotors were replaced at 6k, took it in yesterday because of weird "loose-like" feeling in steering, but they said nothing was wrong with it. From this forum, looks like the steering column needs lubed, but I wanted to mention it in case it helped diagnose the 4wd whine.

Thanks