Odd Behavior in 4x4?

2000 Tacoma 4x4 (manual hubs)

When in 4x4 (Hi) there seems to be some low vibrations in the truck when accelerating/loading the drive system, such as going up hills.

Mostly noticeable over 40 mph, dont seem to notice it at low speeds.

If i remember correctly it even makes the vibration when traveling at 40+mph and clutch is in (no acceleration).

Can feel vibration/hum in steering wheel.

Ideas?

 

First thing to do...is lubricate/grease your driveshaft ujoints.

 

copy that - its on my list but sounds like needs to be done now

thanks