@bethridg @GreggPDX - You are both, indeed, correct. The manifold recessed fasteners are 7mm hex. However, on the passenger manifold I cannot get purchase - a 7mm hex key just spins in both of the recessed fasteners. Someone has been here before me and stripped them both good (odd, because the manifolds do not look like they have ever been off and no service record suggest that they have). I get purchase just fine on the drivers side. This is a problem, as a need the manifold off. This afternoon I installed the flywheel, pressure plate and clutch and then moved on to the starter. The starter will not come close to mating because of a bracket that secures a coolant and oil return line occupies the same space that the starter solenoid wants to have. To modify necessitates the removal of the manifold. Bah. This weekend I'll get to grinding down a 12mm socket in an attempt to get it on the outer hex as per @GreggPDX's suggestion.