The heavy destroyer and medium cruiser are up, but I am not very good at explaining what you need to do to use both ships in the game. I left them in the same folder as they use the same textures, and all I did was modified the ship list to point to the correct ship. For the medium cruiser and its variants it would be assets/models/Ghdd/gcm.mod
For the heavy Destroyer and its Variants Its assets/models/Ghdd/ghdd.mod
hope you can understand what you need to do.
And heres the link
http://www.sfc-mods-r-us.net/