The Lexus GS300 tail light utilizes 7443 and 1157 bulb sizes for the rear illumination system. Data for the specified components covers the period from 1993 through 2004.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The two bulb types present across all tail light positions on the Lexus GS300 are the 7443 and the 1157. Both are ANSI-standard dual-filament bulbs rated at 12V with a 21W/5W power split, where the higher wattage filament serves braking or turn functions and the lower wattage filament serves running light functions.
The 7443 is a T20 wedge-base bulb, meaning it is held in its socket by friction rather than a locking mechanism. The 1157 uses a BAY15d bayonet base, which requires a quarter-turn to lock into place. These two base types are physically incompatible with each other, so one cannot be substituted for the other without a socket adapter or housing modification.
For the inner tail light, the Lexus GS300 used the 1157 through the 1996 model year and into the 1997 model year up to August 1997. From the 1998 model year onward through 2000, the inner tail light position takes the 7443.
The outer tail light on the GS300 followed the same 1157-to-7443 transition pattern, with the 1157 specified for 1995-1996 and for 1997 models produced before August 1997, and the 7443 specified from 1998 through 2005.
The August 1997 production cutoff noted for both the inner and outer tail light positions indicates a mid-year specification change, meaning two different bulb types may be correct for 1997 GS300 vehicles depending on their specific production date.
Despite the different base designs, the 7443 and 1157 share identical voltage and wattage ratings at 12V and 21W/5W, reflecting that both were designed to meet the same functional output requirements within the ANSI standardization framework.