So my speculation is somewhat correct in that they changed the design after probably a 2 year run of the mould and then changed during 74. As I have a 74 VC-SPORT with it's original cowl with 2 vents and all cowls onwards had 2 sets of vents.
Thanks Max, nice easy explanation. I had been talking about it in private messages with other vc enthusiasts and I thought it was worth putting it up on the forum.
