Follow these instructions to keep the ATF cooler cleaner working properly:
Replace the two magnetic nonbypass spin-on filters after every 20 hours of use, based on the hour meter, or when you notice a restriction in the ATF flow.
Check the level and condition of the fluid in the tank before each use.
Replace the ATF in the tank when it looks dark or dirty.

Gauges
TripMeter
This meter shows the number of miles (U.S.) or kilometers (Canada) driven since
you last reset it.
There are two trip meters: Trip A and Trip B. Switch between these displays by
pres ...
Flywheel Inspection
Remove the ring gear holder.
Inspect the ring gear teeth for wear and damage.
Inspect the clutch disc mating surface on the flywheel for wear, cracks,
and burning.
...
Output Shaft (Countershaft) Speed Sensor Replacement (M/T)
M/T
Raise the vehicle on a lift.
Disconnect the output shaft (countershaft) speed sensor connector (A).
Remove the output shaft (countershaft) speed sensor (B).
...