Check the front driveshaft...
..especially the CV joint right at the transfer case - which is basically right under the gas pedal...
8 bolts and you can get the drive shaft out to have it checked (or check it yourself) - you can also drive it to see if the noise goes away.
'97 TJ, 4.0, lots of good parts...
Sold and gone to Michigan
'06 LJ, 4.0, 42RLE, 241OR+2LO, HPD30, Rubi44, 4.88s
4.5" RE Superflex Short Arm, Bilstein 5100s, 9.5CTi, 35" MT/Rs... (phase 2)
Phase 3=Home-made 3-link front>>Phase 4=Trussed, RCVd, Rubi44 front>>Phase 5=ORIs (already purchased) and linked rear