* Check the VIN: The Vehicle Identification Number (VIN) contains information that can help identify the original transmission. You'll need to consult a decoding chart specific to 1983 Chevrolet trucks. These charts are often available online through sites specializing in vehicle history. Note that the VIN might indicate the *original* transmission, but it could have been changed later.
* Look at the Transmission Case: The transmission itself often has markings stamped or cast into the case. These markings may include numbers and/or letters that identify the transmission type (e.g., TH350, SM465, 700R4). You might need a flashlight and possibly a mirror to see these markings, as they're often located on the side or bottom of the transmission.
* Examine the Shift Linkage: The shift linkage pattern and the number of gears can offer clues. A three-speed automatic will have a different linkage than a four-speed manual.
* Consult the Owner's Manual: If you have the original owner's manual, it should specify the transmission type.
* Check the Build Sheet (if available): If you're lucky enough to have the original build sheet for the truck, it will definitively state the transmission installed at the factory.
* Under the Hood: Some markings related to the transmission may be found on components related to the transmission, like the bellhousing or linkage.
* Look for the Parts Tag (rare): Sometimes a parts tag indicating the transmission remains on the truck.
The most reliable methods are checking the VIN (with a decoding chart) and directly examining the transmission case for identifying markings. Remember safety first; take precautions before working under the truck.
