Sorry to drag up something old. But I have this filter housing too. What is the sensor in this just under the oil filter to the right hand side. Its the little piece under the letter 9 on the filter in your picture.
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Hey - I never did figure it out
The oil pressure switch I used was just behind the filter - you can just make out the yellow below the fuel line. Neither of those sensors were connected
From memory I used supply oil from the manifold that runs along the block, there are a series of 1/8 plugs that run alongside. This is filtered and cooled oil, used to supply engine bearings and other critical components
I did find an Engine Manual somewhere, complete with schematic that were used for reference