Jeff : Looks like I can't be of a lot of help, but here is what I found.
I have 3 different Salesman's Price Books for 1967 : October and November of 1966, and May of 1967. All only have "List Prices.
I have 2 Ford Price Books (each about 3/4" thick) that are for 1967 ; November 1966, and May of 1967. Again, both only show :List Prices. As a mater of fact, none of the Ford Price Books that I have after 1957, show anything except List Prices. 1957 and earlier, show both List, and Dealer Prices. It is interesting though, that starting in November of 1966, Ford noted that they would include a loose leaf "Wholesale Discount Table" with all Ford Price Books. Prior to then, these had to be purchased separately by the Dealer (if they wanted one).
Striking out on the price books, I went to my "Ford Parts and Service Merchandising News" magazines. These were typically 16 page "magazines" sent only to Dealers each month. These included marketing of parts, Dealer promotions, new parts and accessories, etc. Until 1967, these almost always included both list prices and Dealer Costs of items "showcased". In 1967 (possibly because of the now included Wholesale Discount Table), rarely does one find both List and Dealer Prices noted.
In looking through these, I found both the 1965 and 1966 AM-FM's listed with both list and Dealer Cost noted (copy of each attached). However, in 1967, Ford elected to not "showcase" the 1967 AM-FM, most likely since the AM-FM was now offered as a Factory Option, and not only as an Accessory like the 1965 and 1966's.
An interesting side note here is that the 1965 AM-FM (C5ZZ-18805-CA) was not introduced until August of 1965, yet apparently was shortly after replaced by the 1966 AM-FM (C6ZZ-18805-BA). The 1966 wasn't shown in the Ford Parts and Service Merchandising News until March of 1966. Yet, in the November 1, 1965 Ford Price Book, a price is listed for the 1966 AM-FM, but for the 1965 AM-FM, it shows "NS" (not Serviced).
Thus, if the C5ZZ was truly available as advertised, it was for a very short time before it was replaced by the C6ZZ.
I know, unfortunately, that this doesn't answer your question, but, nonetheless, it was an interesting exercise. I suppose that you could take the same discount shown for the 1965 and 1966 AM-FM's (21% in each case), and apply it to the 1967 List Price, and it might be close, but just a guess.
Bob