Pulled my valve covers off and found out that my camshafts are just fine and not worn out. My rocker arms also looked fine. What a relief !!! Replaced the camshaft plastic oilers that were cracked and all is well now. Thank God !!! But the tapping noise coming from the top end of the #5 or #6 cylinder is still making noise at all times when the engine is operating. I will go ahead and have those lifters replaced and hope that it will solve the problem. Has anyone replaced lifters in a 420 SEL before have any comments or suggestions ? Is a valve spring compressor necessary ?