The 168 bulb follows the ANSI standard recognized in both the US and Canada. It is a miniature wedge bulb in the T10 form factor, rated at 12V and 4.9W, placing it among the lower-wattage bulbs used in automotive marker lighting.
The 7443 bulb also carries ANSI standardization for the US and Canada. It is a dual-filament wedge bulb in the T20 form factor, rated at 12V with a 21W/5W output, where the two wattage values correspond to its high and low filaments respectively.
The front side marker position on the Acura CL uses the 168 bulb across all listed model years, spanning 1997-1999 and 2001-2003.
The rear side marker position on the Acura CL uses two different bulb sizes depending on the model year. The 168 bulb is specified for 1997-1999, while the 7443 is specified for 2001-2003.
Because the front and rear positions share the same 168 bulb for 1997-1999 model years, a single bulb type covers both marker positions on those vehicles.
For 2001-2003 model years, the front and rear side marker positions require different bulb types, as the front retains the T10 168 while the rear transitions to the T20 7443. These two form factors are not interchangeable due to differences in physical size and wattage.
The T20 form factor of the 7443 is physically larger than the T10 form factor of the 168, which means the socket housings for the rear side marker on 2001-2003 models are designed specifically for the larger bulb and will not accept a T10 fitment.