Maximum displacement: 350 cc/rev
Maximum torque: 6,226 Nm (4,593 lb-ft)
Maximum speed: 97 rpm
The other model numbers you mentioned seem to be associated with various excavators:
303C and 303.5C are models of Caterpillar mini-excavators. Here are some specifications for these excavators:
Operating weight (303C): 3,530 kg (7,778 lbs)
Operating weight (303.5C): 3,650 kg (8,047 lbs)
Engine power (both models): 22.4 kW (30 hp)
Maximum digging depth (303C): 3,380 mm (11 ft 1 in)
Maximum digging depth (303.5C): 3,670 mm (12 ft 1 in)
ZX30 is a model of Hitachi mini-excavator. Here are some specifications for this excavator:
Operating weight: 2,760 kg (6,085 lbs)
Engine power: 18.2 kW (24.4 hp)
Maximum digging depth: 2,690 mm (8 ft 10 in)
I hope this information is helpful! Let me know if you have any further questions.