Would like an educated guess before I take it in for repair.....
Have a 98 Grand Cherokee Ltd. 5.2 77,000miles While in low 4 wheel drive on pavement I floored it and by 3rd gear I heard a "metal clunk" from front left wheel. It still shifts OK but there is a vibration that is most noticeable from 25mph. Will not drive it over 30mph. It steers OK, will go into reverse, can select between low and regular gears, trans still is smooth shifting, brakes ok. Only noises are coming from front left wheel area. Have not seen any fluid leaks. What do you think it is and how much to repair? Thanks!

sounds to me like your having a problem with the cv axle inexpensive and easy to relace

its not recomended that you use 4 low on pavement, it can cause damage to the transfer case and other components if the use is more that maybe crossing a road to get from one trail to another

Thanks for your input 71maverick, hope you are right!
dnuccio - I think I am learning this the hard way. thanks for your post info.