Dodge A100 Truck Dome Light Bulb Size

The Dodge A100 Truck dome light requires bulb size 1003 or 1004 depending on the specific configuration of the interior lighting component. Data for the bulb sizes covers the range from 1964 to 1968.

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
1968	1004
1967	1003
1966	1004
1964-1965	1003

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. Variant of 1157. 12V, 21/5W.	1004
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1003

Other Locations

Additional Notes

The two bulb types specified for the Dodge A100 Truck dome light across the 1964-1968 model years are the 1003 and the 1004, both of which are ANSI standards recognized in the US and Canada.
The 1003 bulb is a single-filament type rated at 12V and 21W, fitted with a BA15s bayonet base, which is a single-contact base with a 15mm collar.
The 1004 bulb is a dual-filament type rated at 12V with a 21/5W output split across its two filaments, fitted with a BAY15d bayonet base, which is an offset dual-contact base with a 15mm collar.
The BAY15d base of the 1004 and the BA15s base of the 1003 are physically distinct, as the former uses two offset contact pins while the latter uses a single contact pin, making the two bulbs non-interchangeable despite their similar appearance.
The 1004 is noted as a variant of the 1157, a widely used automotive bulb, meaning the two share the same BAY15d base and dual-filament configuration, though wattage ratings may differ between specific variants.
The Dodge A100 Truck used the 1003 bulb for the dome light in the 1964-1965 model years, then switched to the 1004 in 1966, reverted to the 1003 in 1967, and returned to the 1004 in 1968.
Because the 1003 and 1004 alternate across model years rather than following a single consistent specification, the correct bulb for a given Dodge A100 Truck dome light is determined strictly by the individual vehicle's model year.