1961
Kenworth Model 521
Kenworth's tilt-cab 521 allowed maximum trailer length under the pre-1982 federal length laws. Built with Kenworth's trademark attention to driver comfort, the 521 featured a wide cab, curved windshield, and Detroit or Cummins power — making it a favourite for the new Interstate highway system.
COE / Cabover
Technical Specifications
| Engine | 12.7L Detroit Diesel 6V71T |
| Horsepower | 275 hp |
| Torque | 1,200 Nm |
| Transmission | 13-Speed Fuller Manual |
| Drivetrain | 6×4 |
| GVWR | 31,751 kg |
|---|---|
| Payload | 20,000 kg |
| Towing | 38,000 kg |
| Fuel Type | Diesel |
| Emissions | Pre-EPA |
| Sleeper | Integral sleeper |
| Length | 7,200 mm (cab) |
| Width | 2,489 mm |
| MSRP Range | $30,000 (1961 US) |