I have a 94 Nissan Quest with a VG30E engine and like a lot of owners of the Quest/Villager I am having some issues with an exhaust manifold. Mine developed a leak in the bellows in the flex joint. I managed to remove the rear header with some effort and have obtained a replacement. In the course of removing the old header, I torqued off one of the studs. Also, I found that the two outermost studs at the extreme ends of the header had long since sheared off. I initially tried to extract the stud from the engine block without success. The particular port I am focused on is the left most port on the engine. In this instance, the port has four tapped holes of which only two are required to secure the header. I have a plan of attack to drill out the stud completely but to do so with some accuracy, I need to know the precise bolt pattern for the studs. The diagonal dimension is about 78.29 mm center to center estimated from the gasket but the pattern is rectangular; not square. Can someone provide me with the horizontal and vertical stud spacings? Fiddling around with whole numbers, 57.6mm W x 53mm H seems to come close.
Thx in advance.

Welcome aboard!

I can't imagine any resource that would have that info. I suppose if I were doing it, I'd use the manifold itself to get a measurement, even if it meant laying the flange face-down on a piece of paper and tracing the holes.

I've had success with this process: https://www.youtube.com/watch?v=VzwEskjits4
Requires no precision measuring, and should accomplish your goal.

Let us know how it goes!

Horizontal and vertical spacing? For the bolt centers? No idea what you'd need those dimensions for.

Nissan had a well known problem of VG30 exhaust studs shearing off, it has happened to me. The later VG33 engines went to a 10mm stud, instead of the 8mm you have. If you can get it out without damaging the threads, just use a NEW stud of the correct size. If you butcher it, upgrade it to the 10mm stud of the later engines.