As I understand this Frank, the number of louvres has varied over time. Where there are 'none' like runabouts or base spec 4/4's there must still be a handful (four each side?) for the heater intake in front of the bulkhead. I've always believed that until the advent of the Roadster the louvres all face backwards, so the air is 'extracted' on the move (with the exception of the heater louvres which, being in a high pressure zone admit air even though they face the 'wrong way'). The Roadster had reversed louvres on the sides only because the Series One takes air in from the nearside. The Series Two does not have the same intake system so presumably can revert to conventional louvres. Mine has eight a side.
Why (some) 4/4's are like that I don't know. Maybe all models were like that from 04 for a while? Looking at my collection of 'nice Mog' pictures, the later cars all seem to have reversed side louvres.
