I'm afraid I probably can't answer many of the specific 'hands on' details of your question. I can tell you that the shop that replaced the manifolds (4 broken head studs) on my '97 Expedition 5.4l used the Dorman parts. They were very experienced with servicing the 5.4 and recommend the Dorman brand parts. They say they are less expensive but better than the OEM parts (they said if you set them side by side on a table, the Dorman looks and feels better/stronger). I've had no problems since.