Here is a picture it is behind the battery, let me know if you have questions. Thanks.
The main computer and the transmission computer are the same thing.....They may have sent you the wrong thing.....This is called a PCM which is a Powertrain control module which controls engine and transmission functions. Some vehicles have a ECM Engine control Module and TCM Transmission control module which has seperate functions but not this vehicle. Let me know if you have questions, thanks.