Skippy the reason I want to replace the timing chain is I own the car since 08 and did not know the maint. history on car when I bought it and since I probably put 50,000 miles on it an M.B. mechanic told me The chain should be replace soon after I bought it. I did not precisely measure the stretch in degrees on it as I did not have the proper dial indicator to measure it but I will do that soon. I'm hoping that by replacing the chain it will put my fuel injection timing more in spec. and make the car run better. I will do a lot more research on replacement before doing it.