I have two big drawers in my pickup bed for tools and supplies I use at work. I made a plywood carcass with center divider for the two drawers (also made with plywood). The carcass extends from the front of the bed to 8" from the tailgate. It is full width. Drawer height is 12". Drawer length is 6'. Drawer width is about 24". Both drawers have a cabinet pull on the drawer front.
About every two or three years, I need to apply some wax onto the bottom of the drawers so they slide nicely. Actually, I don't want them to slide freely since they would be sliding in and out. Even with a few hundred pounds in each drawer, they are easy to slide out and in. Total weight of the carcass and drawers empty is around 200 lbs. The drawer that has fasteners and hardware, chains and hitches, and misc. power tools in the three sections of the drawer weighs about 400 lbs. The other drawer weighs less, when full, about 200 lbs.