They were planning a upgrade kit (with plans) for the FT Mustang to make it an FT-82 -- one extra fuse, mid-wing section and tail plank -- but it's never risen high enough in the list to go to release. There's always something newer/better/more-sought-after on the list bumping it off . . . much like the Mig-3 and Shindin
There was also some traffic about releasing it with/shortly after the mini Mustang, but still, other priorities.
It's REALLY not that hard to scratch build your own:
- Build a center section the width of the wing root, in the same shape as the wing, long enough to go through both fuselages, then glue the regular wings onto this. Like the blunt-nosed versa add-on, It's all straight lines and right-angles, so it's really easy to scratch out. Dihedral gage will need to be cut in half, since you'll have two bends in the wing.
- elevator/H-stab is just a plank spread between the tails -- easy to cut it long then trim it to size.
- Rudder servo goes in one tail, elevator goes in the other. you can either mount a slave-strut for the rudder in the other tail, or let that rudder flap in the breeze.
- Span the gap with servo extensions to the RX and power each ESC with an independent pack . . .or run battery wires while you're at it -- your call.
If you put both tail servos on the same side, I've got an article on how build an adaptor to easily let you route two signals down a servo wire, instead of one signal and BEC power. might put the roll-balance off a touch, but would greatly simplify the routing. I'll dig it up if you're interested.