GMC W5500 Forward front and rear side marker bulbs use 194 size bulbs for illumination. The replacement chart covers 1988 to 2001 production years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The GMC W5500 Forward uses the 194 bulb across all listed front and rear side marker positions, making it the sole bulb type present in these specifications.
The 194 is an ANSI-standardized miniature wedge bulb in the T10 form factor, rated at 12 volts and 3.78 watts, recognized across both the United States and Canada.
The T10 wedge base design means the 194 bulb seats without a separate socket locking mechanism, relying instead on friction from the wedge-shaped base against the housing contacts.
At 3.78 watts, the 194 operates at a relatively low wattage, consistent with its role in side marker lighting rather than primary illumination functions.
For the front side marker, the GMC W5500 Forward carries the 194 bulb across model years 1988-2001, with the Tiltmaster sub-model designation noted specifically for 1993-2001.
The Tiltmaster designation on 1993-2001 front side marker entries indicates a cab-over tilt configuration, which may affect housing access and bulb replacement procedure compared to non-designated years.
Rear side marker coverage in the specifications spans 1988-1995, with the Medium Duty sub-model designation applied to the 1988-1992 entries.
The rear side marker entries for 1993-1995 carry no sub-model designation, while those for 1988-1992 are specifically attributed to the Medium Duty variant, indicating a fitment distinction within the same model line.
Because the 194 is an ANSI-standardized bulb, it is produced by multiple manufacturers, though physical interchangeability does not guarantee identical light output or longevity across all versions bearing the same designation.