I have a 2004 f150 Heritage model v-6; the Catalytic converter to exhaust manifold nuts rotted off. They are completely gone. I was wondering if someone could tell me the size and thread of nut I would need to replace them.
Are they metric or SAE, even that would help, then I could buy a few sizes and try them?

The nuts are completely gone leaving only the studs. It seems odd to me. First the recall on the gas tank straps, mine were about gone and now bad nuts allowing the crossover pipe to just dangle about. When did things get so bad at Ford?

 

I decided to bite the bullet and go to the local Ford dealer and just buy the nuts. Part number N800419-S301. Two nuts came in each bag. I would think that means they would ring it up two of part # N800419-S301, but no there are 4 nuts so they did 4 times the horrible price of 4.74 after tax $20.10 for parts I should not have needed to begin with. Not the world I am used to...

 

Sorry didn't see this earlier, they are metric M12. Any decent hardware store should have them, my local ACE and a true Value have a huge selection of metric in stock

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