HArd to get exact numbers without contacting Kevin Marti. In general terms (from his records) there were 1127 GT convertibles build.
REAL GT convertibles are fairly rare but "new" ones keep turning up
You don't report the specifics about the car (engine, trans, colors) and placing true vlaue varies alot from day to day. A correct concours level car with a good engine, trans and color combination would likely bring mid-high 20's if the right owner/builder and right buyer were brought together. At the same time a really nice, restored car (same one) might only bring high teen's if advertised national or taken to auction.
MCA Shelby Gold Card
Mustang & Shelby research, documentation, and help.
Where sharing with one .. means sharing with all
Nice car, as you can see I like them. Anyway, try http://www.nada.com I have found this site to have fairly accurate price values... as for true worth..... well that's up to you. It's only worth what someone is willing to pay for it. I'm sure you could get at least the average price according to nada if it's in good shape. As for rarity only 14,746 verts out of 299,864 Mustangs were made in 69. Even fewer were GTs. In fact not very many were. If you want to know the exact numbers contact Kevin Marti. http://www.martiauto.com If that's not the correct URL then try the link on my website. Good Luck!
Saw your post on classifieds for selling this car. Why didn't you just come out and say you were asking for the info to try to sell it for a fair price? What are it options, VIN, door data tag info, etc. Have you decided on a price?