Project history: 18 boats were built by Wuhan SY, 4 by Jiangnan SY. This is a Chinese-built derivative of the Soviet Project 633 with slightly more engine and motor power and a redesigned outer hull. Boats of Type 035 (ES5C) were differed from Type 033 by new machinery. Some sources say about single-screw and triple-screw schemes, but plans of usual twin-screw construction with more powerful diesels and motors are more real. In fact first two submarines were built with machinery power equal to Type 033 but with new hull form and electronics. Type 035A received new machinery (modernised diesels and much more powerful electric motors). Mass-production version Type 035G differs from previous versions by ability to launch wire-guided Yu-3 torpedoes, new SQZ-D sonar suite including French-designed DUUX-5 sonar (Chinese name is SQG-2B) and combat control system. Last series unit, Changzheng 308, was lengthened by 2 meters to add section with AIP. Last Type 035B submarines received new fin, similar to later Type 039, new electronics, ability to launch Yu-4 torpedoes and, in future, cruise missiles from TTs.