Recently I have bought a 94 Aero. As there is a missing bolt at the exhaust manifold the head has to be taken to be repair (all costs to be paid by vendor). I think the timming chain has to be taken out too for head extraction. My question is .... which timing elements have to be changed? I...

Recently I have bought a 94 Aero. As there is a missing bolt at the exhaust manifold the head has to be taken to be repair (all costs to be paid by vendor). I think the timming chain has to be taken out too for head extraction. My question is .... which timing elements have to be changed? I...