Is this gear whine or what?

Got my New XJ yesterday '99 Sport 4.0L, Aw4, np242, d30/8.25. Anyways this Jeep is very very clean and very tight, but I as I am driving I notice around 65-67mph on up it starts this rythmic (sp?) hoaning kinda sound and the faster you go the fatser it gets and louder. Its like a whooooan...whooooan...whooooan...whooooan...whoooo an..sound and there is like 1 sec. inbetween the next whoooan sound. (Sorry best I can do)

Anyways I thought it was coming from the front, either maybe the driveshaft or d30, but now it may be the 8.25 or heck I don't know...Any help? I am about to start modding this thing and what all its little issues solved before I dump money into it.

Im' not sure what it is, but I think my MJ is making the same noise. MIne gets louder with more throttle though. It does it at city speeds also. Im' pretty sure it is either my tranny (Pukegoat BA10/5) or the rearend (Dana 35).

The only fix I have for it (till something breaks) is to turn the stereo up.

Sorry I couldn't be of more help.

LOL, its okay.

BTW the Jeep only has 63k miles. I was told it could be the tires or bearings also, but I have no clue.

I was told its the front ds and its normal.

From the sound you describe it sounds like gear whine buddy. I had a 93 5.0 with 3.73:1 gears installed in the rear end and while they said minimal gear whine was normal I heard what you described in mine. I also heard it in an xj that I almost bought. I didnt buy it due to that but it didnt mean it was bad I am just anal when it comes to automobiles running perfectly. But some things to try is draining the gear oil it could just be old, low or not the right weight. try a thicker weight such as 80w 90 or the such. AS for the rear being messed up, there is so much mechanics or what have you that go on inside that pumpkin that if something were out of line or messed up, you would have found out by now when your car came to a screeching hault due to a locked up differential. So try chaning your fluid front and rear i did that when i bought my xj with only 25,000 miles on the clock and if it proves to be something else at least you can rest assured that your differentials are in proper working order

Thanks, I am leaning towards gear whine or maybe my tires.

I took my front driveshaft off and it still did it, which I am kinda glad about because I am getting new tires and regearing soon too.

Can you feel the vibes or just hear them? I would first check out the ujoints in the rear drive shaft, then the front. Check your tranny mount as well.

An out of balance drive shaft can cause just what you say. The less it is out of balance, the higher it tends to be felt. My scraped up shaft vibes at 55+ and slacks off at about 70

I had the same thing and when I changed my fluid in my rear diff, it went away.

Thanks guys, I checked my u-joints and they all seem tight. I think either I am low on fluid or either just have gear whine. Since I just got it off the lot I am sure the fluid is low.