Upper stage / space tug - in development 2004. The upper stage for the Chinese Next Generation Launch Vehicle was a modification of the CZ-3B upper stage.

The stage used a version of the Lox/LH2 YF-75 engine, simplified for improved reliability. The stage was of hammerhead form, with the upper LH2 tank with a diameter of 5 m, and the lower liquid oxygen tank with a diameter of 3.35 m. The total propellant was 22,900 kg with a burn time of over 600 seconds. Empty mass had not yet been released and was estimated. Gimbaled engine used a gas-generator turbopump.

Length: 12.00 m (39.00 ft). Basic Diameter: 3.35 m (10.99 ft). Span: 5.00 m (16.40 ft). Mass: 26,000 kg (57,000 lb). Main Engine: YF-75. Main Engine Thrust: 156.000 kN (35,070 lbf). Main Engine Propellants: Lox/LH2. Main Engine Propellants: 22,900 kg (50,400 lb). Main Engine Isp: 448 sec.