Hello I’m new to this so I hope y’all can bear with me! I have some questions on my 2006 Jeep liberty. I’ve taken it to the shop a few times for this rumbling noise that comes from underneath the jeep. I take it into the shop and they have provided different issues it could be wrong with it. First it was the rear brakes, which I have replaced. Second was the front brakes which I went ahead and had the shop replace. Still the same noise coming from underneath the jeep. Then it was the rattling from the heat shield on the catalytic converter which I fixed myself. this last time they replaced the driveshaft; they said that was the noise. Now they are telling me I need a new transfer case! I don’t know very much about this system and would like some good advice. Also the rumbling starts getting worse around 60 miles an hour to where it scares me to drive it. Thank you!