Question. What size motor does your car have? Mine has the 350 5.7L and I had a similar problem a couple years back that turned out to be the oil pressure sending unit on the back right side of the engine. It seems that I have a high pressure oil pump (over 60psi even hot) and it will blow them out after some time. Hopefully that is the problem. If not that seal, how good are your valve cover gaskets or the intake manifold gasket? Definitely easier to fix.
The clicking thing is hard to diagnose but I have an issue where my back exhaust manifold bolt on the right side will back itself out over some time. The last owner decided to put antiseize on the bolt to keep it from sticking ever again. Apparently it works
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Best of luck.
Keith