In the early 1970s the range underwent a change and the 250 model became the 300 model, the special 350 was launched and the 480 and 500 models replaced the 450 model, before evolving into the 540 Special.
Nei primi anni '70 la gamma si modifica e il modello 250 diventa il modello 300, nasce il 350 special e i modelli 480 e 500 sostituiscono il modello 450, per poi evolversi in 540 special.