Fun discovery: if the PO of your car was dumb and lost a handful of the big convex conical intake and exhaust manifold mounting bridge washers (and nuts, and studs...), you can use the ones from the Pathfinder. This means just about any Nissan dealer will have them in stock, so no waiting for orders. They're still not cheap (couple dollars apiece), but they're no more expensive than the "correct" ones.
Dave

 

And the Pathfinder ones are exactly the same?

 

If they aren't exactly the same, they're within a mm in diameter (I and O) as well as in thickness. It's hard to tell for sure because my originals (the few I have left) are so rusty that who knows what the original dimension was precisely. I'll try and snap a pic tonight if I get a chance. The conical and convex aspects are a match. And it clears the tight spaces to mount the 6:1 MSA header.
Dave

 

Good to know!