65 cuda rear top rails..Help

Sorry to hear about your dad, I bet he's watchin' you with a smile. If you're talking about the moldings that ride along the top of the quarter panels leading up to the tailpipe, I recall they just pop out with a plastic knife. So they should have an arrow-shaped metal clip attached to the bottom of the molding. You just line up the clips with the holes in the quarter, a light rap with your fist, and they're in. Hopefully he left the clips attached to the molding.