I have a 1999 ML 320 with 130000km. I just have my center bearing replaced. What were the symtoms in your truck. My truck's probelm was a constant whirring above 20km/hr. You don't need to have the steering rack replaced for that alone but in my case when I have my truck inspected I also found out that my inner tie rods were worn and those were replaced along with the center bearing under the canadian mercedes signature class extended warranty. Other things that was recently replaced was a plugged catalytic convertor that lead to engine misfire and a leaky transmission oil cooling hose, all replaced under extended warranty.