You more than likely have 3.42:1.

2003 Chevrolet Silverado Handling, Ride & Braking Standard Features

- ABS
- 3.42:1 axle ratio
- Four disc brakes including four ventilated discs
- Electronic brake distribution
- Immobilizer
- Fullsize steel rim under body spare wheel
- Wishbone front suspension with stabilizer bar independent with torsion springs , beam rear suspension rigid with leaf springs