Final answer:
FedEx vehicles that do not require DEF will not have a DEF level gauge, while newer vehicles that do require DEF will typically have a gauge.
Step-by-step explanation:
FedEx vehicles that do not have a DEF (Diesel Exhaust Fluid) level gauge are typically older model vehicles that do not require DEF for operation. DEF is a liquid that is used in diesel engines to reduce emissions. It is stored in a separate tank and injected into the exhaust to break down harmful gases.
Newer FedEx vehicles that have diesel engines and require DEF for operation will usually have a DEF level gauge to monitor the fluid level. This gauge may be located on the dashboard or near the DEF tank.
In summary, older FedEx vehicles that do not require DEF will not have a DEF level gauge, while newer vehicles that do require DEF will typically have a gauge to monitor the fluid level.