I've posted on these before,
http://choosingscars.blogspot.com/2006/12/parade-mustang-with-rumble-seat-1-of-4.html#links
Suprised the hell out of me, one went up for auction at Barrett Jackson and they didn't promote it... wow, missed chance there to spread the word. I'll be looking through the magazines to see how many were at the auction and noticed this rarity
http://www.barrett-jackson.com/carlist/cardetails.asp?In_AuctionID=221&In_LotNumber=428.1
Went for 48 thou.
"This particular package was a joint effort by Ford and Autocraft of Dearborn, MI. The option was not shown on the build sheet or Ford window sticker because the conversion was done after assembly. It was a "Blossom-Time" sales promotion offered only during April 1969 to certain Michigan dealers. Documented by 2 different magazine articles, it is still un-certain exactly how many were done. This one is believed to be the only one in "Meadowlark Yellow". This one was built April 16, 1969 and delivered to Jack Dykstra Ford in Lansing, MI."