seeking input on 2006 e350 4matic purchase

I'm looking for some advice about how wise it is to purchase a 2006 e350 4matic with just about 100k miles.
Car has had all its services done on time, has had every problem that's come up addressed and repaired in a timely fashion.
I see no sign of balance shaft repair in the work history which concerns me. Once one of these reaches 100k is that still likely to occur, or can I assume if it's made it this far it's balance shaft is alright
General advice or input regarding how well this car can be expected to do as the mileage builds is appreciated.
Thanks so much!