FORD 2015 E-450 - Manual (Page 181)

The transmission fluid should be in this range if at normal operating
temperature (150°F-170°F [66°C-77°C]).
The transmission fluid should be in this range if at ambient temperature
(50°F-95°F [10°C-35°C]).
180 Maintenance
2015 Econoline (eco)
Owners Guide gf, 1st Printing, June 2014
USA (fus)