replacing head gaskets and running into issue with manifold, on 1990 Cadillac DeVille

trying to remove the manifold to replace head gaskets and while I have removed many bolts and the lifters, rocker arms, etc however I am not locating the standard heavy duty bolts that would hold manifold in and nothing seems to be removing the manifold. Please advise where exactly these main bolts are and how many I can expect so I can move forward.

Asked by for the 1990 Cadillac DeVille
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What engine. do you have in this car?