2000 Sahara

I've got a 2000 Sahara with 78,000 miles on it and it's started making a whining noise when accelerating through a turn, such as in a parking lot. I am thinking it'a the U-Joint, but people keep telling me that it would be making a squeeking noise if it were the U-Joint. I've also got a transmission leak that appears to be coming from the transfer case. Anyone know how much that repair will set me back?
Thanks for your help!

Possible Power steering pump? Check level and see if it does it when setting and turn far left and right to see if it does the same? I wouldn't think a leak would be much to fix. Mechanics run around $40 an hour or around that and the cost of the seal. If you let it go it could cost you lots in the future. Hope this helps.

Thanks, I'll have to look into that!