1. Check the VIN (Vehicle Identification Number):
* Location: The VIN is typically found on the driver's side dashboard, near the windshield, and on the driver's side door jamb.
* Decoding: The 10th digit of the VIN often indicates the transmission type. You can use a VIN decoder online (like [https://www.vindecoder.com/](https://www.vindecoder.com/)) to help you decipher the information.
2. Look at the Transmission Identification Tag:
* Location: The transmission tag is usually located on the passenger side of the transmission case, near the bell housing.
* Information: The tag should have the transmission model number, which will indicate the type of transmission.
3. Check the Owner's Manual:
* Original Manual: If you have the original owner's manual, it should list the transmission type for your specific Blazer model.
4. Inspect the Transmission Case:
* TH350: This three-speed automatic transmission has a distinctive "350" casting on the case.
* TH400: This three-speed automatic transmission also has a "400" casting on the case.
* 700R4: This four-speed automatic transmission is generally larger than the TH350 and TH400 and has a "700R4" casting on the case.
5. Consult a Mechanic:
* Professional Diagnosis: If you're still unsure, a qualified mechanic can quickly identify the transmission type. They can also inspect the transmission for any potential issues.
Common Transmissions in 1989 K5 Blazers:
* TH350 (3-speed automatic): Common in earlier model years.
* TH400 (3-speed automatic): More powerful than the TH350, but less common.
* 700R4 (4-speed automatic): Introduced later and offered with some options.
Remember: The specific transmission in your Blazer will depend on the trim level, engine size, and other factors. The above methods should help you pinpoint the type of transmission you have.
