DEFINITELY replace all of them on the side you're working on. And you don't
need to go to a Nissan Dealership to get the work done. Go to the Nissan
Parts Department, ask for new exhaust manifold studs (all they sell now are
the "improved ones"), then take them to your nearest reputable exhaust shop.
It will save you $200-$300. And the end product will be the same. This is
based on my experience only - make your own decisions please.
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