Complex sentence: During the 1970s many PA Crestas were modified and customised, and the model was very popular with fifties revivalists; many were driven by teddy boys and were very much seen as part of the rock'n' roll image.
Split into simpler sentences: During the 1970s many PA Crestas were modified and customised. The model was very popular with fifties revivalists; many were driven by teddy boys and were very much seen as part of the rock'n' roll image.