Mack TD700 Dome Light Bulb Size

The Mack TD700 dome light requires a 561 bulb size for proper installation within the interior overhead lighting fixture. Data for the specified component covers the range from 2011 through 2017.

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
2011-2017	561

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Festoon bulb, 44mm length, end-cap contacts. 12V, 12W.	561

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Additional Notes

The 561 is the sole dome light bulb size listed for the Mack TD700 across all specified model years.
The 561 bulb is classified as a festoon type, meaning it is cylindrical in form and makes electrical contact through metal caps at each end rather than through a base socket.
The 561 operates at 12 volts and draws 12 watts, which is consistent with standard 12-volt automotive electrical systems.
The 561 carries ANSI standardization recognized in both the United States and Canada, indicating it conforms to a defined set of electrical and physical tolerances shared across manufacturers.
The 561 has a 44mm length, which is the critical fitment factor for festoon bulbs, as the housing retains the bulb by tension against its end caps at a fixed span.
The 561 bulb size applies to the Mack TD700 for model years 2011-2017 without variation across that span.
Festoon bulbs of differing lengths are not interchangeable even when voltage and wattage ratings match, as an incorrect length will result in either a loose fit or an inability to seat the bulb within the housing.