My thought is MAYBE Non AC cars could get the F, The N and the G ??? dunno... but if so, there is no reason they get the one welded on valve cover ( like @400sforever got which is a non AC car ), the one to valve cover bolt won't be used and wires used could be the earlier ones which are shorter ( the reason they are that long is because the longer run on this setup no matter what firecore crew says ), however as far I recall, never have seen a diff PN for the spark plug wires set for BB on my 74 parts catalog ( AC and non AC ). Dunno if @ODZKing can check it, because I'm in Spain and my catalog is in Venezuela.