On my 2009 2AZ, the tube seals are integrated (at least with OEM gasket)
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When the old gasket stands at attention and has to be shattered out, you can bet it wasn't sealing well
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Some people claim they've gotten counterfeit spark plugs from RockAuto/Amazon/eBay, so I'm back to brick and mortar for them
SK20R11's are under $10 each with a coupon code @ Advance Auto