No, these are some sort of threaded inserts or standoffs - there are smaller bolts that are within those inserts that seem to hold the entire assembly tight against the block. I will have to get into it over the weekend and take it apart to see what I am working with. Thanks for your input - I have just never seen anything like this before.

any other feedback is welcome and encouraged.

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1969
Model 220 gasoline
Chassis: W115.010