Expand your fleet! Convert your TOS turtleshell antagonists' (who didn't have turtleshell foreheads at the time, but that's beside the point) ships by utilizing these modular nacelles. You will need the D-7 that comes with your 2500 AMT Original Series Set. The opening slots at the top of the nacelles connect to the pylons.
Based on an original design by Rob Willson, offered with his permission.
Check out the detail