The timing chain has never been changed. Was inspected at around 355M. My mechanic said on a scale of 1 to 10 (10 being best) it was a 5 based on wear and a 1 based on age. What is the recommended interval for timing chain replacement? I know the MB V-8's are a lot more sensitive in this area. Valves have been serviced per maintenance schedule. Is $700 the going rate for a timing chain replacement on a 617? While the timing chain is being changed what other items would be a good idea to service at that time? I don't have the time to do the timing chain. Are the aftermarket brands of timing chains as good or better than the factory chains?