Sounds like they are gun platforms that were changed. Wish it could be a cheat code ( just for relieving stress sometimes), but it is not. Could it be you have a corrupted table? I have noticed that when Freespace get a ship table entry it does not understand. It defaults to a Ulysses. I have extracted game files from the vps and changed them in Fred. Then I place the files in their respective folders in the data folder to test. Try and see if this works for you. Just remember to place the table files in the tables folder, in the data folder, before loading Fred.
or you can just try another download link.