Is there and pics or videos on replacing the coolant crossover gaskets?
I have a hidden leak and I'm suspecting the crossover gaskets.

Welcome to the forums
Have you pressure tested the system? I would want to know for sure where the leak is coming from first, the cross over gasket is a bit of work!
There does not seem to be any YouTube videos on this procedure that I could find.
A factory service manual would be handy to access in this situation.
I managed to find this link, possibly other members may chime in on this one as well.
Here is the link to FSM procedure outlined:
http://www.justanswer.com/cadillac/6...northstar.html
Hope this helps.

Thanks for the reply and advice. I have not pressure tested the system. I'm going by the fact that you can't see the leak and others have said this is common with the symptoms that I have. I will pressure test the system and I have the gaskets needed.

Thanks for the link