Do you drain the Torque Converter?
Also, any leaks?
if so, read this:
"LIGHT TRUCK: 1987-1996 BRONCO
1987-1997 F-150, F-250, F-350
1997 EXPEDITION, MOUNTAINEER
This TSB article is being republished in its entirety to include 1997 model year vehicles.
The transmission may have low fluid level and/or may have either a shift concern and/or an engagement concern. This may be caused by transmission fluid leaking from the transmission into the transfer case through the transfer case input seal.
Replace the transfer case input seal. The new seal should reduce the possibility of fluid leaking from the transmission into the transfer case.
Fluid Capacity . . . . . . . . . . . . . .24 Pints
this prob includes the tc.