* Transmission Type: The biggest hurdle is ensuring the transmissions are the same type (automatic or manual) and have the same number of gears. Even if they are both, say, 4L60E automatics, there can be subtle internal differences between years.
* Bolt Pattern: The transmission's bolt pattern to the engine and transfer case (if applicable) must match. While likely similar, slight variations between model years can exist.
* Wiring Harness: The electrical connections might be different. The 2000 model might have different sensors or solenoids that aren't compatible with the 1997's wiring harness.
* Computer Compatibility: The vehicle's computer (PCM) needs to be compatible with the transmission. A newer transmission might not communicate correctly with the older PCM. This is a significant factor.
In short: While it might seem like a simple swap due to being the same vehicle, you absolutely need to verify the transmission part numbers (found on a tag on the transmission itself) against both your 1997 and the donor 2000 Blazer. Even then, a professional transmission mechanic should be consulted. Attempting this swap without expertise could lead to significant problems or even damage to other components. Finding a used transmission from a 1997 or very close model year is the safest route.
