Cabin Headliner:  Pre-1977 headliners were installed like a 1955 Chevy.  Those are light and easy to replace. Post '76 headliners have vinyl gluded to double sided sticky foam.  Heat releases the sticky over time.  When "I" install a new headliner, it's a major job.  I strip everything down to the bare metal.  The area where the rear windows go are stripped, primed, and painted with white Imron. This prevents corrosion under the window sealant. 
----->>> NOTE: If you own a 77 and later Grumman, your W&B is wrong! The weight of the foam headliner isn't correct.

I installed a separate rear cabin switch. Passengers can turn on their own light.