What is the low beam headlight bulb size for a 1978 GMC K25?

The 1978 GMC K25 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 K25?

The high beam bulb size for the 1978 GMC K25 is N/A.

Why are my 1978 GMC K25 headlights dim?

Dim headlights on a 1978 GMC K25 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 K25 fog light?

The 1978 GMC K25 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 K25 single or dual beam?

The 1978 GMC K25 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 K25?

Yes, the 1978 GMC K25 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 K25 change headlight bulb sizes from the previous year?

No — the 1978 GMC K25 uses the same bulb sizes as the 1977 model. This configuration has been consistent across the 1975–1978 generation.

Is the 1978 GMC K25 the first or last year to use H6024 bulbs?

The 1978 GMC K25 is the last year in the 1975–1978 generation to use the H6024 bulb for the low beam headlight.

How do I change the headlight on a 1978 GMC K25?

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 K25?

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 K25 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 K25?

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 K25 is the last model year to use this bulb configuration (1975–1978).

Fitment Guaranteed for 1978 GMC K25

What Size Bulbs Does a 1978 GMC K25 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 K25 Have?

Lighting on the 1978 GMC K25 is managed by a total of 2 bulbs, covering everything from primary headlights to signal indicators. 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 K25's 1975-1978 production span.

Can You Put LED Bulbs in a 1978 GMC K25?

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 K25 Bulb Size Chart

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

How do the 1978 GMC K25's bulbs compare to other years?

The 1978 GMC K25 uses the same bulbs as the 1977 model.

This bulb configuration covers the 1975–1978 model years. ← 1977

Finding the best installation guide...

Other K25 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