I've heard different stories from different people and mechanics. Just wanted to see what advice I get here for my 1991 300d 602 engine with 210k miles.

1) Some people just check for chain stretch, adjust it, and that's it. Others say to replace the chain, rails, and tensioner. An article I just read said to replace the sprocket too.How many have replaced the sprocket?

2) A general mechanic is going to check the timing chain for stretch, or he can replace the chain for an additional $250. Does the chain need to be replaced?

3) One MB independent mechanic told me not to replace the chain. He said he has never seen a chain break on W124's; they are dual chains and they're NOT going to break. He also told me he checks for stretch through the injection pump, and that there was a service bulletin out that the injection pump also needs to be altered by 1 degree.

....So....what to do? Just check for stretch? Or replace parts? If so which ones? Is a new chain really necessary?