Ford 1999 Explorer Owner's Manual page 264

Filling station information
2
Ensure correct automatic transmission fluid is used for a specific
application. Check the container to verify the fluid is MERCON and/or
MERCON V approved. Some fluids have been approved as meeting both
MERCON and MERCON V requirements and will be labeled as such.
Fluids labeled as meeting only MERCON or only MERCON V
requirements must not be used interchangeably. DO NOT mix MERCON
and MERCON V. Transmission fluid requirements are indicated on the
dipstick or on the dipstick handle. Refer to your Scheduled Maintenance
Guide to determine the correct service interval.
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