From what I can see of the part number, those appear to be the original equipment type plugs...NGK were the stock plugs. Recommended change interval is 48000 kms ( about 29000 miles) which is quite low but if they're the original plugs, you're overdue anyway. V/C gasket and tube seals etc are inexpensive enough at the dealer...available in the current world economy is an unknown. Hard to get a real idea but the gap on those plugs look huge, double check before installing each plug, you should be gapped at 0.028". You have to use feeler gauges on platinum/iridium/ruthenium type plugs and be careful. it's very easy to damage the tip!!