I am finding it interesting to see the posts claiming drop ins are problems waiting to happen. I have a 2001 tundra with Pendaliner with over 96K miles. I have hauled every type of construction and lawn maintanance material you can imagine including landscape rip rap. I had the
liner out a couple of times for cleaning and the pain in the bed was like new. I did not have any water or rust damage to speak of. Where in the world did rust issue come from. To tell you the truth I never saw this as a problem except on old trucks that were already rusting through. In those cases the bed line helped keep things together. Go Figure. The biggest issue for me is keeping from dentin the inside body when dropping in cargo.
As a hunter I also have seen that the pendaliner cleans well. Deer blood is hard to get off the spray in liners and they also fade.