I seem to remember a previous post regarding a leaking sunroof on a Monroe conversion.

I went out last night to move my truck and discovered the headliner is wet on one side around the sunroof.

I checked to make sure the sunroof was closed and it seemed to be.

Any ideas on how to fix this ?

Maybe check your gasket that surrounds the sunroof? That is usually the first thing to wear out.

You might also want to check your cab lights as they can leak too.