Isuzu NRR headlight bulb sizes include 9003 and H4651 for high beam applications, along with 9003 and H4656 for low beam configurations, representing the bulb specifications for this commercial truck model. The replacement chart covers 2005 through 2013 production years with corresponding bulb size data.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Isuzu NRR (Tilt Cab) uses the 9003 bulb for both high beam and low beam headlights across the 2006-2013 model years. The 9003 is a dual-filament halogen bulb rated at 12V with a 60W high beam filament and a 55W low beam filament, fitted with a P43t base.
Because the 9003 carries both filaments in a single housing, one bulb serves both the high beam and low beam functions simultaneously. This is why the same part number appears in both headlight positions for the 2006-2013 NRR.
The 2005 NRR (Tilt Cab) uses a different lighting technology entirely. The high beam position takes an H4651 sealed beam unit, while the low beam position takes an H4656 sealed beam unit. Both are 4x6-inch rectangular sealed beam units operating at 12V.
Sealed beam units such as the H4651 and H4656 are not replaceable bulbs in the conventional sense. When the light fails, the entire sealed unit is replaced rather than an individual bulb inside it.
The H4651 and H4656 are distinct part numbers and are not interchangeable with each other, as each is designated for a specific beam function. Substituting one for the other would result in incorrect beam output.
The 9003 bulb and the H4651/H4656 sealed beam units are not compatible with each other. The 2005 NRR headlight housings are designed around sealed beam technology, while the 2006-2013 housings accept the P43t-based 9003 bulb.
All bulb and sealed beam types listed for the NRR conform to ANSI standards applicable in the United States and Canada, indicating standardized photometric and dimensional requirements across those markets.