popping

VEHICLE: 1996 ZJ Limited Rubicon Express 3.5 Super Ride w/ Rusty's upper rear adjustable C-arms 231 swapped in for the original 249 TC (Novac shifter kit) Rubicon Express Adjustable track bar in the front and in the rear PROBLEM: Steering column at the firewall POPS once when turning past...

hi guys, i have a 98 grand cherokee laredo 4.0 that is popping from under the drivers floorboard when under power in 4wd or turning in 4wd. 2wd is quiet. full time 4wd is not as loud. i have replaced the wheel joints and the front drive shaft joints, no help. is it transfer case time? or is it...