[jmk]

I've replaced the headliner in my 3600.  It was stuck to the inner fiberglass shell using something similar to liquid nails.  It was foam-backed vinyl glued to and wrapped around gelcoated plywood panels.  I was not able to remove the panels without breaking them, so I cut new ones out of marine plywood.  Reinstalling is really just a matter of attention to detail and planning.  It was a significant job.  Not something I would recommend unless you consider yourself handy.