hi i will like to know how many miles before i have to worry about balance shaft going i have 98000 miile on my 06 e350 car was well maintain by dealer all recalls was done but not sure about the balance shaft thankyou

The thinking these days seems to be that the problem can pop up in higher mileage cars as well. If you like, there is a YouTube video on how to do a visual check to assess whether you have an issue or not. It's here--