Peterbilt 372 Back Up Light Bulb Size

Additional Notes

• The 1156 is the sole bulb type specified for back up light fitment across all listed model years of the Peterbilt 372, covering 1989-1995.
• The 1156 is an ANSI-standard single-filament bulb rated at 12 volts and 21 watts, recognized for use in both the United States and Canada.
• It uses a BA15s bayonet base, which is a single-contact bayonet mount with a 15mm collar. The single-contact design corresponds directly to the single-filament construction of the 1156.
• Several model years carry conditional fitment notes tied to headlamp configuration. The 1990 Peterbilt 372 lists a separate entry specifically for vehicles equipped with 4 round headlamps, while a general 1156 entry also exists for that year.
• The 1991 and 1995 model years each include a conditional entry for vehicles equipped with 4 rectangular headlamps, alongside a general 1156 entry.
• The 1989 and 1992 model years each carry a conditional entry for vehicles equipped with halogen capsule headlamps, in addition to a general 1156 entry.
• The presence of both general and configuration-specific entries within the same model year indicates that headlamp type is treated as a relevant fitment variable for the back up light position on the Peterbilt 372.
• Despite the conditional notes referencing different headlamp configurations, the bulb size specified remains 1156 in every case, meaning no alternative bulb type is introduced by any of the conditional entries.