Mack CH License Plate Bulb Size

The Mack CH license plate light requires a single 1891 bulb size for the exterior lighting assembly. Available information covers the specific time period from 1989 through 1997.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
1989-1997	1891

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Miniature wedge bulb (T5). 12V, 2W.	1891

Other Locations

Additional Notes

The 1891 bulb is the sole license plate bulb type listed across all model years of the Mack CH covered by these specifications, spanning 1989-1997.
The 1891 is classified as a miniature wedge bulb with a T5 tubular envelope, a form factor defined by its wedge-style base, which requires no separate socket retainer and connects directly by friction fit.
The 1891 operates at 12 volts and draws 2 watts, placing it among the lowest-wattage bulbs in automotive lighting applications.
The 1891 carries ANSI standardization recognized in both the United States and Canada, meaning the designation refers to a consistent electrical and physical specification across those markets.
The T5 designation in the 1891's classification refers to the tubular glass envelope, with the numeric portion indicating the envelope width in eighths of an inch, making it one of the smaller tubular bulb profiles used in vehicle lighting.
Because the 1891 is an ANSI-standardized type, replacement bulbs from different manufacturers carrying the same designation are expected to conform to the same voltage, wattage, and base configuration as the original fitment on the Mack CH.