Took my engine out because of oil leak and really ruff running. Took the valve covers off and the intake rocker arm bolts for the 7 and 8 cylinders were both broken on the the #7 and #8 had one backed out and the other broke. I put new injectors in, different intake and took turbo out. I'm ashamed to say that there was a socket below one off the rocker arms but not on the other. Any ideas on what could have caused this?