96 would be OBDII, you need a code reader or some sort of scanner to pull codes, but doubt you will find your trans temp issue there anyway.
The F 350 may still be OBD I. Got a friend with a 96 F 350 4x4 with a 5.8 and C6 and it it still OBD I with the EEC-IV computer. It is set up just like my 95 F 350.
If you want to pull codes on an OBD I try HERE.
Ford Fuel Injection has all kinds of info on the OBD I systems.