I have a 2012 "shitbox" at ~31,000KM and it has made the grumbling tranny sounds ever since i purchased it. I even had the entire clutch/flywheel replaced at 2700KM due to the high pitch whine it had. This is the only issue i have had with this jeep so far, but man is it ever annoying! The grumbling noise is most likely the TOB and it you do any river crossings and wash the grease off it will start to whine really high pitched, like a dog whistle. Anyone else notice that the transmission (clutch bellhousing) is wide open at the bottom? Most vehicles have an inspection plate, but ours is just open for the weather and debree to get in...