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1991 GMC R3500 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.

1991 GMC R3500 Bulb Size Chart

PositionBulb CodeAliasesTrim / PackageFactory TypeConfidenceReviewNotesShop
Low BeamH4703—Standard listingHalogenHigh
Pending

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

Amazon
Side Marker194—Standard listingHalogenMedium
Pending

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

Amazon
High Beam9005HB3Standard listingHalogenHigh
Pending

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

AmazoneBay
Brake Light3157CK—Standard listingHalogenHigh
Pending

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

Amazon
Turn Signal Rear3157CK—Standard listingHalogenHigh
Pending

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

Amazon
Tail Light3157CK—Standard listingHalogenHigh
Pending

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

Amazon
License Plate194—Standard listingHalogenMedium
Pending

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

Amazon
Reverse Light3156—Standard listingHalogenMedium
Pending

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

Amazon

1991 GMC R3500 Fitment Notes

Across the 1988-1991 production range, our database shows changes in the listed Low Beam, Reverse Light positions. Use the chart above for this 1991 model, then confirm the bulb number in your vehicle 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 1991 GMC R3500's bulbs compare to other years?

The 1991 GMC R3500 uses the same bulbs as the 1990 model.

This bulb configuration covers the 1990–1991 model years. ← 1990

Finding the best installation guide...

Other R3500 Years

19901988

More from GMC

10010001000 Series15015001500 Series2502500

Other Vehicles That Use H4703 Bulbs

1994 Pontiac Sunbird1993 Chrysler Imperial1993 Chrysler New Yorker1991 Chevrolet Full1991 Chevrolet V35001990 Chevrolet C3500

Frequently Asked Questions

Our database lists H4703 for the 1991 GMC R3500 low beam headlights. Verify the bulb number on your existing bulb and confirm your trim or factory lighting package before buying.

Our database lists 9005 for the 1991 GMC R3500 high beam position. Some vehicles vary by trim, lighting package, or previous housing changes.

Dim headlights on a 1991 GMC R3500 can come from aging halogen bulbs, cloudy lenses, weak electrical connections, or an incorrect bulb. Confirm the listed H4703 size against the bulb in the housing before choosing a replacement or upgrade.

The 1991 GMC R3500 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 1991 GMC R3500 uses a dual bulb headlight system. This means you have separate bulbs for high and low beams.

LED upgrades are available for many H4703 applications, but fitment, beam pattern, dashboard warnings, and road-use legality can vary. Use products that list your exact bulb family, such as H4703, and verify the factory housing before buying.

No — the 1991 GMC R3500 uses the same bulb sizes as the 1990 model. This configuration has been consistent across the 1990–1991 generation.

The 1991 GMC R3500 is the last year in the 1990–1991 generation to use the H4703 bulb for the low beam headlight.

Access varies by engine bay layout and headlight housing. Before disassembly, confirm the listed H4703 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 H4703 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 1991 GMC R3500.