Howdy Again Slade:
There are three possible scenerios; 1st, in an OEM pre-75 head is not Induction hardened nor does it have hardened inserts. 2nd is somewhere in '75 to somewhere in the '76 model year that you would have induction hardened seats on either the exhaust side or both sides. There is no way to tell, visually, if the seats have been hardened by an induction heating process. An experienced machinist could tell once he starts cutting.
3rd, hardened inserts installed are usually visable on disassembly. They are installed by a machining process where the seat is machined to receive an insert which is interference fit and then machined. This is a common upgrade in a head rebuild.
Short of a disassembly and inspection, check the receit on the previous rebuild.
Is that what your needed?
Adios, David
