I have to agree with Alan that it is the 'zeitgeist' of the time, celicas 2000gts, mgb's and fairlady roadsters, s30's, the bleubird (or 510) and the fiat 128.. they all have that same look and feel.
Cars from teh same company would most definatly share styling.. as mostly they where drawn from the same hands.
It is much like the modern volkwagens, seats and alfas they all share styling, and within the brand it is hard to tell the diffrence between a Jetta and a Passat.
And as for that diffrent port thing.... dont give tony ideas, he has allot of ports coming with his job