Back 16 years ago when I installed SSI heat exchangers, I noticed that the exhaust manifold studs on heads 1,2,3 were different in appearance (the stud necks down / is thinner in the length between the threaded portions) from the studs on heads 4,5,6.
This difference in studs leads me to think the 4,5,6 heads had been worked on in the past before I bought the car in Dec 2006. Not only are the exhaust studs different, but when I disassembled the heads from the cam towers I found residue of red crayon marks on the 4,5,6 heads, but not on the 1,2,3 head /cam tower assembly.
So my question for the experts is: are the exhaust studs from heads 1,2,3 (thin in the middle) original as installed by the factory?
I removed the intake and exhaust studs from the heads before I shipped them off to Craig for machining and the exhaust studs on heads 1,2,3 were much more difficult to remove than the exhaust studs from heads 4,5,6. In fact, one stud from head 1 and one stud from head 3 were "welded" in place and the studs broke in half in the thinned area of their length and that was with penetrating old, MAP gas torch heat and my stud extractor tool which worked so well with the head studs in case halves.