Assuming you mean whine and not squeek or squeal you have a bad wheel bearing. Chances are that is gets louder when you turn one direction and quieter when you turn the other. I usually replace the whole hub assembly but I think it is possible to replace just the wheel bearings but they are a pressed in affair and will ultimately cost you close (75%)to same price as just replacing the hub assembly when you figure in "pressing labor".
I'm going with wheel bearing also. You can save money by changing it yourself. A regular shop will have all of the tools you need except for a special tool, which if you know anyone at a local garrage or dealer, I'm sure you can borrow it. I've not had to change a bearing on my ZJ yet, so I'm not sure how differently it works, but it can't be but so different from other 4x4's.
The wheel bearing should be the same as in the xj. Remove the tire, brakes and rotors, hub nut and cotter pin, and then the three hub retaining bolts on the back side of the knuckle. Then hopefully you can tap the assembly out of the knuckle. You can also tap on the partially undone hub retaining bolts and work the hub out that way. That is if your lucky. I had to use a slide hammer, air hammer, air chisel, and a lot of hot wrench and a big puller....all at once
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