Skip to main content

1978 GMC G25 Bulb Size Chart

Bulb sizes may vary by trim, factory lighting package, region, production date, and previous modifications. Verify the bulb number on your existing bulb before buying.

Last database update: May 2026. Manual review status: Not yet manually reviewed.

Verify before buying: check the bulb number printed on your existing bulb, confirm your trim and factory lighting package, and review the seller's fitment notes.
Disclosure: We may earn a commission from links marked Affiliate. Unmarked retailer links may be plain search links. Always verify bulb fitment before purchasing.

1978 GMC G25 Bulb Size Chart

PositionBulb CodeAliasesTrim / PackageFactory TypeConfidenceReviewNotesShop
Side Marker194—Standard listingHalogenMedium
Pending

Verify trim, factory lighting package, and the bulb number on the existing bulb.

Amazon
Low BeamH6024—Standard listingHalogenHigh
Pending

Dual-beam bulb; verify factory housing and lighting package.

Amazon
High BeamH6024—Standard listingHalogenHigh
Pending

Dual-beam bulb; verify factory housing and lighting package.

Amazon

1978 GMC G25 Fitment Notes

Our database shows the same listed bulb sizes for the GMC G25 across the 1975 to 1978 range. Still verify your trim, lighting package, and the bulb number in the housing before buying.

Known fitment limitations

  • factory HID or LED packages may use different parts
  • fog lights may depend on equipment package
  • aftermarket headlight assemblies may use different bulbs
  • regional models and production-date splits may differ

See an incorrect bulb size? Submit a correction.

How do the 1978 GMC G25's bulbs compare to other years?

The 1978 GMC G25 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 G25 Years

197719761975

More from GMC

10010001000 Series15015001500 Series2502500

Other Vehicles That Use H6024 Bulbs

2006 Hummer H12006 Jeep TJ2006 Jeep Wrangler1998 Bentley Turbo R1997 Land Rover Defender 901997 Mazda MX-5 Miata

Frequently Asked Questions

Our database lists H6024 for the 1978 GMC G25 low beam headlights. Verify the bulb number on your existing bulb and confirm your trim or factory lighting package before buying.

Our database lists H6024 for the 1978 GMC G25 high beam position. Some vehicles vary by trim, lighting package, or previous housing changes.

Dim headlights on a 1978 GMC G25 can come from aging halogen bulbs, cloudy lenses, weak electrical connections, or an incorrect bulb. Confirm the listed H6024 size against the bulb in the housing before choosing a replacement or upgrade.

The 1978 GMC G25 does not have a fog light bulb listed in our current database. If your vehicle has fog lights, verify the bulb in the housing or owner's manual before buying.

The 1978 GMC G25 uses a single bulb (dual filament) headlight system. This means one bulb controls both high and low beams.

LED upgrades are available for many H6024 applications, but fitment, beam pattern, dashboard warnings, and road-use legality can vary. Use products that list your exact bulb family, such as H6024, and verify the factory housing before buying.

Yes — the 1978 GMC G25 uses different bulb sizes than the 1977 model. The 1978 generation introduced this bulb configuration.

The 1978 GMC G25 is the only year in the 1978 generation to use the H6024 bulb for the low beam headlight.

Access varies by engine bay layout and headlight housing. Before disassembly, confirm the listed H6024 low beam size on the existing bulb or owner's manual, then follow the service procedure for your exact trim.

Rules for LED headlight retrofits vary by location and by housing type. Avoid products that create glare or lack road-use compliance claims, and check local requirements before using an LED conversion on public roads.

Replacement cost depends on bulb technology, brand, and labor access. Common halogen H6024 replacements are usually cheaper than LED conversion kits. Check seller fitment notes before comparing prices.

Halogen bulbs and LED replacements differ in output, heat behavior, beam pattern, and electronics. A correct bulb code does not guarantee a correct LED beam pattern, so verify physical fit and seller compatibility notes for the 1978 GMC G25.