If you have a stock 6,2 with stock heads- motor serial # will dictate what plug to use and spark plug gap as well. Up to engine serial # 0M299999 takes a completely different plug than engine serial # 0M300000. I take it your motors are year model 2008 ? I can not tell you guys how important engine serial #'s on marine apps really makes a difference as to what parts you have, ordering parts, and service / repair procedures. In this app the early 6.2's have a completely different ECM, and ignition set up than the later ones. Completely different 100 %