People genuinely forget this service exists compared to how ingrained engine oil changes are in everyone's maintenance mindset. Differential fluid degrading gradually and increasing friction on the gears is a real thing that just doesn't get talked about nearly as much.

Vibration at 100 km/h on a JKU is usually driveshaft balance or worn track bar bushings. A Jeep specialist will check both without you having to suggest it.

3,800 with a six month warranty versus 9k for a full swap. That's the difference between a shop that can actually rebuild these units and one that just orders a replacement and bolts it in.