1. **Gather Tools and Materials**: You will need a side-mount truck box, mounting brackets, bolts, nuts, washers, a drill, drill bits, a measuring tape, a wrench, and a marker. 2. **Position the Box**: Place the truck box on the side rail of the truck bed. Ensure it is centered and does not obstruct the rearview or tailgate operation. 3. **Mark Drill Holes**: Use the marker to mark the locations for the mounting holes on the truck bed rail, aligning with the pre-drilled holes on the box. 4. **Drill Holes**: Remove the box and drill holes at the marked locations on the truck bed rail. Use a drill bit that matches the size of the bolts. 5. **Install Mounting Brackets**: Attach the mounting brackets to the truck bed rail using bolts, nuts, and washers. Ensure they are securely fastened. 6. **Secure the Box**: Place the truck box back onto the mounting brackets. Align the pre-drilled holes on the box with the holes on the brackets. 7. **Bolt the Box**: Insert bolts through the aligned holes and secure them with nuts and washers. Tighten using a wrench to ensure the box is firmly attached. 8. **Check Alignment and Security**: Ensure the box is level and securely fastened. Adjust if necessary. 9. **Test the Lid**: Open and close the box lid to ensure it operates smoothly without obstruction. 10. **Final Inspection**: Double-check all bolts and nuts for tightness and ensure the box is stable and secure. 11. **Clean Up**: Remove any debris or metal shavings from the truck bed to prevent rust or damage.

- **Wrenches and Sockets**: For tightening bolts and nuts. A ratchet set with various socket sizes is useful. - **Drill and Drill Bits**: To create holes for mounting the box if pre-drilled holes are not available. - **Measuring Tape**: To ensure accurate placement and alignment of the box. - **Level**: To ensure the box is installed evenly and not tilted. - **Marker or Pencil**: For marking drill points and alignment. - **Screwdriver**: For securing screws, if applicable. - **C-Clamps**: To temporarily hold the box in place during installation. - **Protective Gear**: Such as gloves and safety glasses to protect against metal shards and debris. - **Rubber Gasket or Sealant**: To prevent water ingress and protect the truck bed. - **Rust-Proof Paint or Spray**: To coat any drilled holes and prevent rusting. - **Utility Knife**: For cutting any necessary materials like rubber gaskets. - **Torque Wrench**: To ensure bolts are tightened to the manufacturer's specifications.

Side-mount truck boxes can be compatible with tonneau covers, but compatibility depends on several factors, including the specific design and dimensions of both the truck box and the tonneau cover. 1. **Design and Fit**: Side-mount truck boxes are installed on the side rails of the truck bed, while tonneau covers typically sit on top of or inside the bed rails. For compatibility, the side-mount box should not interfere with the operation or installation of the tonneau cover. Low-profile side-mount boxes are more likely to be compatible as they sit below the bed rails, allowing the tonneau cover to close properly. 2. **Type of Tonneau Cover**: The type of tonneau cover plays a significant role in compatibility. Roll-up and retractable tonneau covers are generally more adaptable to side-mount boxes because they can be adjusted to accommodate the box's presence. Folding and hinged covers may pose more challenges, as they require more clearance and may not close properly if the side-mount box is too high or wide. 3. **Customization and Adjustments**: In some cases, modifications or custom installations may be necessary to ensure both the side-mount box and tonneau cover fit together. This could involve adjusting the mounting brackets or selecting a custom-sized box or cover. 4. **Brand and Model Compatibility**: Some manufacturers offer specific products designed to work together, ensuring a seamless fit. Checking with the manufacturers for compatibility recommendations can be beneficial. In summary, while side-mount truck boxes can be compatible with tonneau covers, it requires careful consideration of the design, type, and potential need for customization. Always verify dimensions and consult with manufacturers or professionals to ensure a proper fit.

To ensure a side-mount truck box is weatherproof, follow these steps: 1. **Material Selection**: Choose a box made from durable, weather-resistant materials like aluminum or stainless steel. These materials resist rust and corrosion. 2. **Seals and Gaskets**: Ensure the box has high-quality rubber seals or gaskets around the lid and openings. These should be continuous and without gaps to prevent water ingress. 3. **Proper Installation**: Install the box correctly, ensuring it is level and securely fastened to the truck bed. Misalignment can create gaps that allow water to enter. 4. **Lid Design**: Opt for a box with an overlapping lid design. This design helps direct water away from the seams and openings. 5. **Drainage System**: Check for built-in drainage channels or holes that allow water to escape rather than accumulate inside the box. 6. **Regular Maintenance**: Inspect the seals and gaskets regularly for wear and tear. Replace them if they become brittle or damaged. 7. **Weatherproof Coating**: Apply a weatherproof coating or sealant to the exterior of the box for added protection against the elements. 8. **Locking Mechanism**: Ensure the locking mechanism is robust and seals tightly. A loose lock can create a gap for water to enter. 9. **Positioning**: Position the box in a way that minimizes exposure to direct rain or water splashes, if possible. 10. **Test for Leaks**: Periodically test the box for leaks by spraying water over it and checking for any moisture inside. By following these steps, you can significantly enhance the weatherproofing of a side-mount truck box, ensuring its contents remain dry and protected.

Weather Guard, UWS, Dee Zee, Lund, and Better Built are considered some of the best brands for side-mount truck boxes.