Blue Motor Holden Heads

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O.K. Guy's Oh and Girls, A Question for you?

Did Holden Make a Early and a Late Model Blue Motor Head?
The Reason I'm asking is as follows: I would normally say that a Blue Motor head has 4 Bolt holes on the side at the front around the #1 spark plug for the power Steering pump.
Problem is I aso appear to have 2 Heads with out these holes in the Head yet seem to be Blue Motor Heads one of the heads is actually on the Van I have with the Blue motor Manifolds on it.
Photo's Below.

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As you can see in the first 3 photo's the only hole on the side at the front of the Head near the #1 spark plug is a hole into the water Jacket for the Temp sender unit which the Red Motor Heads dont have.
The last photo is of another Head which has the 4 Bolt Holes around the #1 Spark Plug which would indicate to me without out looking at the ports to be the standard Blue Motor Head.