300td-- I have pulled engine, all looks good. I thought I would take head in to have freshened up. 265,000 miles on it. Should the pre chambers be taken out at this point. also what is the procedure to set the prechambers as far as the thickness of the seals?? there is a small triangle with what appears to be "norm" on it --on top of the piston, is this a stock MB piston? or reman. I have all the paper work with this car and no sign the engine was ever touched.