The Isuzu NPR uses 168 and 89 bulb sizes for front side marker applications, with 89 bulb size for rear side marker positions. The replacement chart covers vehicle production spanning 1986 to 2013.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 168 bulb is a T10 miniature wedge type rated at 12V and 4.9W, conforming to ANSI standards recognized in both the US and Canada.
The 89 bulb is a single-filament type with a BA15s bayonet base, rated at 12V and 13W, and is classified as a lower wattage variant of the 1156 bulb under ANSI standards.
The Isuzu NPR front side marker position uses the 168 bulb across the 2006-2013 Tilt Cab configuration.
The front side marker on Heavy Duty configurations transitioned from the 89 bulb to the 168 bulb between the 1994 and 1995 model years.
The 89 bulb's BA15s bayonet base is a single-contact fitting, which is not interchangeable with wedge-base sockets designed for the 168 bulb despite both operating at 12V.
The rear side marker position on the NPR is specified exclusively for Heavy Duty configurations from 1986-1994, all using the 89 bulb.
The 168 and 89 bulbs differ substantially in wattage, at 4.9W and 13W respectively, meaning they draw different levels of current even though both operate on a 12V system.
The front side marker on Heavy Duty NPR models from 1986-1994 and the rear side marker on the same configuration share the same 89 bulb specification, indicating socket compatibility between those two positions within that generation.