What is the low beam headlight bulb size for a 1978 GMC C15?

The 1978 GMC C15 uses a H6024 bulb for the low beam headlights. We recommend upgrading to LED for better visibility.

What is the high beam headlight bulb size for a 1978 GMC C15?

The high beam bulb size for the 1978 GMC C15 is N/A.

Why are my 1978 GMC C15 headlights dim?

Dim headlights on a 1978 GMC C15 can be caused by aging halogen bulbs, which lose brightness over time, or oxidation (cloudiness) on the plastic headlight lenses. Upgrading to a H6024 LED conversion kit can provide a significantly brighter and whiter light output.

Which bulb fits the 1978 GMC C15 fog light?

The 1978 GMC C15 typically does not come with factory fog lights in all trim levels. If your vehicle is equipped with them, check the manual as sizes can vary by trim.

Is the 1978 GMC C15 single or dual beam?

The 1978 GMC C15 uses a dual bulb headlight system. This means you have separate bulbs for high and low beams.

Can I install LED bulbs on my 1978 GMC C15?

Yes, the 1978 GMC C15 comes with standard halogen bulbs from the factory, but they can be upgraded to LED. You will need a H6024 LED conversion kit for the low beams.

Did the 1978 GMC C15 change headlight bulb sizes from the previous year?

Yes — the 1978 GMC C15 uses different bulb sizes than the 1977 model. The 1978 generation introduced this bulb configuration.

Is the 1978 GMC C15 the first or last year to use H6024 bulbs?

The 1978 GMC C15 is the only year in the 1978 generation to use the H6024 bulb for the low beam headlight.

How do I change the headlight on a 1978 GMC C15?

Turn off the vehicle and open the hood. Locate the headlight assembly from behind, remove the dust cover or retaining clip, disconnect the wiring harness, twist the old H6024 bulb counter-clockwise to remove it, then insert the new bulb and reassemble. The whole process typically takes 10 to 30 minutes per side depending on accessibility.

Are LED headlights legal for a 1978 GMC C15?

LED bulbs used off-road or in auxiliary lights are legal everywhere. For on-road headlight use, legality varies by state. Many states allow LED retrofits as long as the beam pattern meets DOT standards. For the best legal compliance, choose a DOT-approved H6024 LED kit that is designed as a direct replacement and produces a proper cutoff pattern without excessive glare.

How much does it cost to replace 1978 GMC C15 headlights?

A pair of halogen H6024 bulbs costs $15 to $40, while LED conversion kits run $25 to $60 per pair. If you have a shop do the work, expect an additional $20 to $50 in labor per bulb. Replacing them yourself at home saves the labor cost and usually takes under 30 minutes.

What is the difference between halogen and LED for a 1978 GMC C15?

Halogen bulbs produce a warm yellow light (around 3200K), last 500 to 1000 hours, and draw more power. LED bulbs emit a brighter white light (5000-6000K), last 25,000+ hours, and use less energy. LED upgrades for the H6024 position are available as direct plug-and-play replacements.

The 1978 GMC C15 has a unique bulb configuration not shared with adjacent model years.

Fitment Guaranteed for 1978 GMC C15

What Size Bulbs Does a 1978 GMC C15 Use?

Correct headlight, fog light, and tail light bulb sizes. Sourced from OEM catalog data.

Installation Difficulty

Easy (Plug and Play)

Est. Replacement Cost

$15 - $40 (Halogen) / $30+ (LED)

What Lighting System Does the 1978 GMC C15 Have?

Owners of the 1978 GMC C15 will find a total of 2 lighting elements throughout the vehicle's exterior. It features a standard lighting system powered by a dual-bulb halogen configuration using separate H6024 low beam and high beam bulbs for precise light distribution. This model belongs to the late years of the C15's 1975-1978 production span.

Can You Put LED Bulbs in a 1978 GMC C15?

For a GMC built for the road and trail, LED upgrades provide the high-contrast lighting needed for better obstacle detection. We recommend starting your upgrade with the H6024 low beams, as they see the most use. Adding a matching LED kit later will complete the look and ensure consistent lighting performance.

1978 GMC C15 Bulb Size Chart

Position	Bulb Size	Shop
Low Beam	H6024	Buy H6024 →
Side Marker	168	Buy 168 →

How do the 1978 GMC C15's bulbs compare to other years?

The 1978 GMC C15 changed bulb sizes from 1977. The previous model year used a different configuration.

This bulb configuration covers the 1978 model years. ← 1977

Finding the best installation guide...

Other C15 Years

1977 1976 1975

Other Vehicles That Use H6024 Bulbs

2006 Hummer H1 1998 Bentley Turbo R 1997 Mazda Miata 1996 Mazda MX-5 Miata 1995 Land Rover Range Rover 1991 Mitsubishi Montero