Jackie, I recruited the wife to help with my abs headliner a couple years ago. It's a bear even with 4 hands. As I recall we trimmed front and rear corners. Also removed the rubber trim that finishes out the cab to door area, or as Jockbolter50 more accurately said "the windlace trim inner lip" this helped a lot. We had to trim both sides a bit, then replaced the windlace trim, hiding the edges.
One of my better moves was to glue 3/4" black closed cell foam rubber (similar to an exercise mat)to the cab roof before we installed the headliner. This was part of a total cab insulation projection that really helped with winter comfort and sound mitigation.
The rear is secured by the original cardboard trim, same in the front.
Good Luck, Ron
