What is the low beam headlight bulb size for a 1991 GMC Full?

The 1991 GMC Full uses a H6054 bulb for the low beam headlights. We recommend upgrading to LED for better visibility.

What is the high beam headlight bulb size for a 1991 GMC Full?

The high beam bulb size for the 1991 GMC Full is H4701.

Why are my 1991 GMC Full headlights dim?

Dim headlights on a 1991 GMC Full can be caused by aging halogen bulbs, which lose brightness over time, or oxidation (cloudiness) on the plastic headlight lenses. Upgrading to a H6054 LED conversion kit can provide a significantly brighter and whiter light output.

Which bulb fits the 1991 GMC Full fog light?

The 1991 GMC Full 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 1991 GMC Full single or dual beam?

The 1991 GMC Full uses a dual bulb headlight system. This means you have separate bulbs for high and low beams.

Can I install LED bulbs on my 1991 GMC Full?

Yes, the 1991 GMC Full comes with standard halogen bulbs from the factory, but they can be upgraded to LED. You will need a H6054 LED conversion kit for the low beams.

Did the 1991 GMC Full change headlight bulb sizes from the previous year?

Yes — the 1991 GMC Full uses different bulb sizes than the 1990 model. The 1991 generation introduced this bulb configuration.

Is the 1991 GMC Full the first or last year to use H6054 bulbs?

The 1991 GMC Full is the only year in the 1991 generation to use the H6054 bulb for the low beam headlight.

How do I change the headlight on a 1991 GMC Full?

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 H6054 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 1991 GMC Full?

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 H6054 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 1991 GMC Full headlights?

A pair of halogen H6054 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 1991 GMC Full?

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 H6054 position are available as direct plug-and-play replacements.

The 1991 GMC Full has a unique bulb configuration not shared with adjacent model years.

Fitment Guaranteed for 1991 GMC Full

What Size Bulbs Does a 1991 GMC Full 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 1991 GMC Full Have?

The 1991 GMC Full utilizes a refined lighting configuration featuring 11 distinct bulb positions. It features an extensive lighting system powered by a dual-bulb halogen configuration using separate H6054 low beam and H4701 high beam bulbs for precise light distribution. This model belongs to the late years of the Full's 1973-1991 production span.

Can You Put LED Bulbs in a 1991 GMC Full?

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 H6054 low beams, as they see the most use. Adding a matching H4701 LED kit later will complete the look and ensure consistent lighting performance.

1991 GMC Full Bulb Size Chart

Position	Bulb Size	Shop
Low Beam	H6054	Buy H6054 →
High Beam	H4701	Buy H4701 →
Turn Signal Front	3057NA	Buy 3057NA →
Side Marker	168	Buy 168 →
Reverse Light	1156	Buy 1156 →
Brake Light	3057	Buy 3057 →
Turn Signal Rear	3057	Buy 3057 →
License Plate	194	Buy 194 →
Parking Light	3057NA	Buy 3057NA →
Tail Light	3057	Buy 3057 →
Map Light	906	Buy 906 →

How do the 1991 GMC Full's bulbs compare to other years?

The 1991 GMC Full changed bulb sizes from 1990. The previous model year used a different configuration.

This bulb configuration covers the 1991 model years. ← 1990

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Other Full Years

1990 1989 1988 1987 1986 1985 1984 1983 1982 1981 1980 1979 1978 1977 1976 1975 1974 1973

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