I hope that you have better luck than me. Two years ago I broke the heel detachable pice of my Tecnica TNT's from 1997. I got in touch with Tecnica distributors in Spain but nobody carried the stock. I tried to contact Tecnica in Italy via e-mail, but they never replied. Finally, I went to a ski shop that rented Tecnicas and got a pair of heel pieces from a later model which, after significant cutting and grinding, I was able to adapt. Incredibly, some months later, while sharpening the edges of my skis in a small shop in a small ski-resort, I asked the guy just in case and he was able to produce them out of a mountain of left overs that he had in a corner.
My advice: call your retailer. If it doesn't work, call the US importer or contact the manufacturer. If you get them, buy two pairs, so that you have spares (they are cheap). If not, go the DIY way by trying to get something relatively similar and adapting it.