The Series I had a Getrag gearbox and 4-pot front brakes, whereas the Series II onwards has a ZF gearbox (smoother change) and 6-pot brakes. Also, the rear suspension has been changed in the Series II to reduce the amount of drive-line shunt.
The Series II is generally known at the 'works' as the Federalised Aero 8, as it was developed for the American market and some 21 cars were written off in crash-testing.
Cheers
Brian
