I am surprised this isn't on the market, it would be very easy to reproduce (compared to my GT seals). I am going to my extruder today to pick up some more material. I will ask about it. I don't have a notchie so I don't have a sample of the seal to work from.
Is your Fastback GT's trunk seal shot? My Gen IV replacement GT trunk seals with miter double bonded corners are now in production. $95 shipped to the US (contact me for international shipping rates) More info can be found here GT Trunk Seal Project