If you replace, use 18ga finish nails. It seems that is what is used everywhere in my rig. The length can be determined by carefully removing one from the existing trim piece. We just had the large slide trim pull off. Packed up and loaded the fifth wheel in 30 minuets do to a mandatory fire evacuation. The cabinet next to the slide opened up while traveling do to the way it was packed. The slide trim caught on the door knob when I opened the slide. Pulled the fasteners out carefully using a needle nose pliers. Straightened one out, measured the length, and then purchased a 18ga pneumatic finisher nailer. The door survived and the knob was slightly bent and straightened out. You can predrill a hole smaller, use a standard finish nail, a nail set, and then fill the hole with colored wax pencil. i did not want to do this method for such a large piece.