You can measure the thickness of the manifold flange and the machined area for the nut and cut the OEM stud to that length with a cutoff wheel or hacksaw. Clean up the thread end and you're good to go. You will need to do this for either one or two of the rear studs, I can't remember. You just need to make sure the end of the stud isn't touching the face of the machined area when everything is tight.