Ford 2000 Mustang Owner's Manual page 224

Filling station information
3
Service refill capacity is determined by filling the transmission to the
bottom of the filler hole with the vehicle on a level surface.
4
Indicates only approximate dry-fill capacity. Some applications may
vary based on cooler size and if equipped with in-tank cooler. The
amount of transmission fluid and fluid level should be set by the
indication on the dipstick's normal operating range.
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