If it isn't broken don't fix it. If you want to check its worthyness, just take off the valve cover and turn the engine by hand until the mark on the camshaft thrust washer lines up perfectly with the line on the cam stand. Take a flashlight and look at the degree marks on the crank balancer on the front and read the mark. If it is equal to ar less than 5 degrees you are OK. If not then think about replacement.
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