Ford F-700 License Plate Bulb Size

Additional Notes

• The Ford F-700 uses the 1157 bulb for the license plate position across all listed model years, spanning 1970-1998.
• The 1157 is an ANSI-standardized bulb type recognized across the United States and Canada, meaning it conforms to a defined set of electrical and physical specifications shared by all compliant manufacturers.
• The 1157 is a dual-filament bulb, meaning it contains two separate filaments within a single envelope, each operating at a different wattage.
• The two filaments in the 1157 operate at 21W and 5W respectively on a 12-volt circuit, with the lower-wattage filament typically serving a continuous or parking function and the higher-wattage filament serving a brighter signaling function.
• The 1157 uses a BAY15d bayonet base, which is a two-pin offset bayonet mount. The offset pin placement is a deliberate fitment control, as it prevents the bulb from being inserted in the wrong orientation, ensuring each filament connects to its correct circuit.
• Because the BAY15d base uses offset pins, it is not interchangeable with single-pin bayonet bases such as the BA15s, even though the physical housing may appear similar in size.
• The consistent use of the 1157 across the entire 1970-1998 span of the Ford F-700 indicates no change in the license plate bulb specification throughout the vehicle's listed production range.