4 wheel drive not engaging correctly. placed vehicle on jacks and attempted to engage 4wd. grinding noise from passenger cv joint, both back wheels spun independently but neither of the front wheels would spin. Able to spin the passenger front wheel but the cv joint does not turn with the wheel however the drivers front tire and cv joint do turn as they should(together). Could there be a problem with the vacuum assist for the 4WD system as well. I'm pretty sure I'll need to replace the cv joint for the passenger side and quite possibly the hub assembly for that same side.

You probably have one or more bad ball joints in the steering on the front end. This truck should have grease zerks on the ball joints. If you greese everything and it gets quite, then it is the ball joints. However a WARNING. If the ball joint was squeaking and grinding, it should be replaced. Have a good mechanic check it out. Its hard to do yourself without the proper tools and knowledge. This is possibly a dangerous situation and something could come loose on the front end and you lose the ability to control the vehicle.
There are other possibilities, like snow and ice build up between the tires. Or bad wheal bearings. Jack the front end up, and rotate the wheels. They should spin freely with no noise. Next grap the wheel top and bottom. There should be no play.

If this is a four wheel drive vehicle it is a possiblility you have bad CV joints or universal joints which transfer power to the wheels. To check this, engage the 4x4, set the parking brake, and jack up the front end. Grap the wheel and try to rotate it, it should not move at all. . If the CV joints are out, you should be able to hear noise when you do this.

You probably have a front drive splined disconnect assembly that has gone bad. This assembly engages the front differential when 4WD is selected. Below is a figure of the item, it is on the passenger side of the differential area.

driving in 4wd on hard surfaces produces what is known as torque wind up as the wheels cannot slip so the variations of distance going around corners , dips in the road etc place considerable strain on the transmission , transfer case , drive lines and diffs
that is why it is difficult to get out of 4wd unless you drive with 2 wheels on a grass verge to relieve that torque wind up
as for the noise check wheel bearings and the cv ("U") joint at that wheel as there appears a proble where the dog teeth in the hub are not engaging properly or are jumping out of engagement

problem cv joints and or "U" joints and or worn slip joints in drive lines
no make model year listed so impossible to know exactly

i've been told it was the 4wd actuator located on the passenger side near were the cv joint goes in to the front axle a good test is to floor jack it up so both wheels are off the ground and have someone on the other side , put in nutrual turn both wheels one way at same time and the 4wd drive shaft should turn if not its your actuator, costs about $86 for anew actuator and takes about 5 mins to change once you have the tire off

Try removing the front drive shaft from the transfer case to the front differential. With the vehicle on 4 jack stands and the front drive shaft removed attempt to place the vehicle into 4 WD. You may have to start the engine if the vehicle uses a vacuum actuator module to engage the front wheels. When you get an indication that the vehicle is in 4WD try turning the front wheels by hand and see it you hear the same grinding noise .... engage the hubs and try again. Usually if the transfer case is ok then the problem is in the front differential or one of the many universal joints that connect all of the elements together. Check the U joints on the front drive shaft for play as well as the U joints on each of the front wheels.

Most likely wheel bearing or cv joint issue. look for a ripped open cv boot. I believe that year used cv joints instead of regular u-joints. Hope I helped. Thanks

1. I would suggest that you engage your 4WD while you are in full stop and/or safe range of 5mph, however as claimed by the local dealers your vehicle is capable of engaging even while driving. Engage your 4WD while moving only when necessity requires.
2. That clicking noise while turning extreme right or left would be the birfield of your axle and would only mean your front hub is still engage even though you have disengaged transfer case.
Have your front hubs cleaned of old lubricants or grease due to non usage. dont use grease as lubricants, use thick oil such as gear oil or silicone oil. and use your 4WD every now and then.

Do this first then check if you still feel somtehing is loose on your suspension and others.

Check your cv (constant velocity joint) , It may have a big clearance which is the source of the noise when turning left or right and when 4wd is engage. Juts like front wheel drive cars, if the cv joint is with clearance it will tend to sound in the left or right turns. It is not exactly clicking sound , nmore like knocking sound , low in pitch, but not heavy.

Could be a few things. Bad ball joint, cv joint, or others. But I'ld start with the CV joints. Basically, your axle shaft. First way to tell if that's the prob would be to put truck in 4 wheel drive, LOW gear. This will lock up all four tires. Then jack up that corner of truck. If the tire only moves a little before you can't anymore, it's fine. But if you can spin your tire completely, odds are it's your cv joint.