My 2006 4.2 supercharged has clicked past 222,000 miles. There are a few things that need doing, like replacing the alternator which is making a squeezing noise, replace the viscous fan which makes a clickING noise when cold and regas the air con.

While I'm doing all those I'm wondering whether it would be a good idea to do some preventative maintenance like changing the timing chains. Do they ever need doing on these engines? Anything else worth doing at the point considering the high mileage and that I intend to keep using it for quite some years?