Frequently Asked Questions About GMC TopKick Truck Cab Lights

Will these cab lights fit my specific year GMC TopKick model?

Most aftermarket cab lights are designed to fit GMC TopKick models from 2003-2009 (C4500, C5500, C6500, C7500, and C8500 series). However, fitment can vary based on whether your truck has a factory-installed cab light wiring harness. Pre-2003 models may require additional modification or different mounting hardware. Always verify the specific product listing matches your truck's year and model number before ordering.

Do I need to drill holes in my cab roof to install these lights?

Yes, most GMC TopKick cab light installations require drilling five evenly-spaced holes across the cab roof. The standard spacing is typically 6-8 inches apart, center to center. Some trucks come pre-wired with a roof harness and may have dimpled marks indicating drill locations. We recommend using a template (often included with quality light sets) and applying rust-preventive primer and sealant to all drilled holes to prevent water intrusion and corrosion.

What's the difference between LED and incandescent cab lights for my TopKick?

LED cab lights draw significantly less power (typically 80% less), last 50,000+ hours compared to 2,000 hours for incandescent bulbs, and provide brighter, more consistent illumination. LEDs also generate less heat, reducing lens discoloration and cracking. While LED sets cost more upfront, they eliminate frequent bulb replacements and reduce electrical system strain. Incandescent lights are less expensive initially but require more maintenance over time.

Can I install cab lights if my TopKick didn't come with them from the factory?

Yes, you can add cab lights to any TopKick, but trucks without factory cab lights will require running new wiring from the lights to your fuse box or headlight switch. This typically involves routing wire through the headliner, down the A-pillar, and connecting to a switched 12V source. Many installers tap into the parking light circuit for automatic operation. Professional installation typically takes 2-3 hours and may be recommended if you're not comfortable with automotive electrical work.

What style and lens color options are legal and available for GMC TopKick trucks?

Amber/yellow is the only DOT-approved lens color for forward-facing cab marker lights in all 50 states. Style options include classic round dome lights, rectangular LED bars, and aerodynamic teardrop designs. Clear or smoke lenses are available but may not be street legal in all jurisdictions. Most TopKick owners choose either OEM-style amber dome lights for a factory appearance or modern LED strips for improved visibility and durability. Always check your local regulations before installing non-amber colored lenses.