Frequently Asked Questions About Peterbilt 357/378 Day Cab Conversion

Will these day cab conversion kits fit my specific year Peterbilt 357 or 378?

Our day cab conversion kits are designed to fit Peterbilt 357 models from 1987-2001 and Peterbilt 378 models from 1986-2001. However, there can be slight variations between model years, particularly in mounting hole patterns and frame rail spacing. We recommend measuring your existing sleeper mounting points and comparing them to our kit specifications before ordering. If you're unsure about compatibility, contact us with your VIN number and we can verify the correct kit for your truck.

What tools and skills are required for installation, and how long does it typically take?

Installation requires basic automotive tools including wrenches, sockets, drill with metal bits, and a grinder or cutting tool for removing the sleeper. Most conversions take 8-12 hours for experienced mechanics or 16-20 hours for first-time installers. Critical steps include cutting the sleeper cab, welding or bolting the rear cab panel, installing the window (if included), and sealing all joints properly. Professional installation is recommended if you lack welding experience, as improper sealing can lead to water leaks and cab damage.

What's included in the conversion kit, and what additional parts might I need?

Standard kits include the rear cab panel, mounting hardware, weather stripping, and detailed instructions. Depending on your chosen kit, you may also receive a rear window assembly and interior trim pieces. Additional items you might need include primer and paint to match your cab, seam sealer or body caulk, interior insulation material, and potentially new air and electrical line fittings if you're rerouting systems. Some customers also purchase our matching headache racks or light bars to complete the look.

How does converting to a day cab affect the truck's weight distribution and handling?

Removing the sleeper typically reduces weight by 800-1,500 pounds, which shifts the weight distribution forward. This can improve maneuverability and fuel economy but may affect ride quality, especially when running empty. Many operators report needing to adjust fifth wheel position forward by 6-12 inches to maintain proper weight balance. You should have your truck's alignment checked after conversion, as the change in weight can affect tire wear patterns and steering response.

What are the different style options, and how do they impact the finished appearance?

We offer flat panel conversions for a clean, professional look and curved panel options that better match the original cab contours. Window options include single rectangular windows, dual square windows, or solid panels for maximum strength. Finish options include bare steel (requires painting), primed surfaces ready for paint, or powder-coated black. The curved panels with integrated windows provide the most factory-like appearance, while flat panels offer easier installation and lower cost. Consider your intended use - vocational trucks often benefit from solid panels, while highway trucks typically prefer windowed options for better visibility.