Answer
Jun 10, 2025 - 08:42 PM
The 2003 Chevy Express 2500 was available with two primary automatic transmissions, depending on the engine and drivetrain configuration:
- 4L60-E 4-speed automatic
Found on lighter-duty models equipped with the 4.8L V8 (LR4) or some versions of the 5.3L V8 (LM7). Commonly used in rear-wheel-drive (RWD) applications. - 4L80-E 4-speed automatic
Used in heavy-duty models with the 6.0L V8 (LQ4) and select 5.3L configurations, especially with all-wheel-drive (AWD) setups.
Which one you have depends on the engine and drivetrain combo. To confirm your exact transmission, check the RPO (Regular Production Option) code sticker — usually found inside the glove box or on the driver door jamb:
- M30 = 4L60-E
- MT1 = 4L80-E
These codes tell you exactly what transmission you have from the factory.
