Yes, the front driveline spins all the time, although it is only engaged at the transfer case in 4WD. If 4wd was engaged, the driveshaft wouldn’t spin but you might get the other front wheel to spin in the opposite direction.
Some things to check:
Transfer-case-side CV joint on the front driveshaft. The rubber boot tends to crack and disintegrate, it loses its grease, and then starts to vibrate as the joint slowly deteriorates. This joint can be replaced without replacing the whole driveshaft. See driveshaftparts.com for a replacement.
Intermediate shaft between the passenger side CV and the front diff. The splines tend to go after a while, leading to vibration. If you replace the right CV or intermediate shaft, do them both at the same time.
Either The right or left CV might be going. Check the rubber boots to see if they are cracked and are shedding grease.
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AtTheHelm Front Recovery System & Roof RackM116A3 Trailer build thread: viewtopic.php?f=72&t=77997