rubber - the staples are needed if yer gonna fake the piece on the bottom against the frame [not available repro], but there's correct repro rubber pieces available for the back edge that have a slot that fits snuggly on the inner and is 'captured' against the cab, no fastening required - originally stapled so it stayed with the panel on the line until installation

Bill


Moved over to the Passing Lane

"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir
"When we tug a single thing on an old truck, we find it falls off" ~ me
Some TF series details & TF heater pics