I saw that same ad and wondered "where the heck did he get these figures?" He seemed so cocksure about it. And I don't know what he was blathering about "dealer installed disk brakes" -- that's just silly. They were always factory installed (would require changing spindles, MC, junction block, as well as the hub, disk, hoses and calipers).
I believe you are correct -- at least up though the 1967 model year, there are no comprehensive breakdowns, only totals. You can find out how many 4 speeds were sold, and how many convertibles, but not how many 4 speed convertibles, for example. See this page:
http://www.440magnum-network.com/info/tech/1967barracudatotals.shtml
