* 4L60-E: This is a four-speed automatic transmission and was very common in the 2003 Trailblazer.
* 4L65-E: A slightly more robust version of the 4L60-E, also a four-speed automatic.
To know *for sure* which transmission is in *your* specific 2003 Chevy Trailblazer, you need to:
1. Check your vehicle's identification number (VIN). You can use online decoder tools that take the VIN and provide detailed information about your vehicle's specifications, including the transmission.
2. Look at the transmission itself. This is more difficult and requires some mechanical knowledge. The transmission case usually has identifying numbers cast into it.
3. Check your owner's manual. This should specify the transmission type.
Once you identify the correct transmission, you can then find compatible replacements. Note that while some transmissions might *seem* compatible, internal differences (torque capacity, etc.) can cause problems. It's crucial to get the correct transmission for your specific Trailblazer model and engine.
