To know for sure, you must determine the following:
* Engine size: Was it a 4.3L V6, a 5.3L V8, or a 6.0L V8?
* Transmission type: Was it an automatic or a manual transmission? If automatic, what is the number of speeds (4 speed, etc.)? You can usually find this information on a sticker on your driver's side doorjamb or in your owner's manual.
Once you have this information, you can consult a parts catalog (like those available at auto parts stores) or a reputable online resource for used parts to find compatible transmissions. Simply searching for "2002 Chevy Blazer transmission" without specifying the engine and original transmission will give you inaccurate results.
Important Note: Even with the correct engine and transmission type, there might be minor differences in year and model that affect compatibility. It's best to double-check with a mechanic or parts specialist to ensure a proper fit before purchasing a used transmission.