Chevrolet Astro front side marker bulbs utilize 194 or 194NA size, while rear side marker bulbs use 194 size. The replacement chart covers 1985 through 2005 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 194 bulb is an ANSI-standard miniature wedge type with a T10 form factor, rated at 12 volts and 3.78 watts. It is recognized under both US and Canadian standards.
The 194NA shares the same T10 wedge form factor, voltage, and wattage as the 194 but features natural amber glass, which produces a colored output without the use of a tinted lens or housing filter.
The Chevrolet Astro uses the 194 bulb for the front side marker across the 1985-1999 model years, with no headlamp-type condition applied during that period.
From 2000-2005, the front side marker fitment on the Astro splits into two variants: the 194 applies to vehicles equipped with halogen capsule headlamps, while the 194NA applies to those equipped with sealed beam headlamps.
Because the 194 and 194NA are physically identical in their T10 wedge base and electrical ratings, the distinction between them in the 2000-2005 front side marker position is one of glass color rather than socket compatibility.
Installing a 194 in place of a 194NA on a sealed beam headlamp-equipped vehicle would result in a clear rather than amber light output at the front side marker position, which may affect compliance with lighting color requirements.
The rear side marker position uses the 194 bulb across the entire 1985-2005 model range, with no headlamp-type condition applied at any year.