Complex sentence: The only component that has remained the same is the engine; in the mid- 1990s there was a production of over 900 missiles (compared to 3,000 Exocets and 6,000 Harpoons).
Split into simpler sentences: The only component that has remained the same is the engine. In the mid- 1990s production exceeded 900 missiles (compared to 3,000 Exocets and 6,000 Harpoons).