EDIT: You are in luck! Found the first two, took me a minute to realize it looked familiar. You can find this ship via my Typhon Pact mod under the Assets/Model folder as: Excaliburx.
https://www.moddb.com/mods/sfciii-typhon-pact-mod/addons/typhon-pact-v4-0I don't believe we modified this model at all from the original file (see below).
As far as the third ship, this is semi-cannon. It's a Bellerophon Cruiser/Light Cruiser. You can find the model file in its entirety from my MirrorrorriM mod
https://www.moddb.com/mods/sfciii-typhon-pact-mod/addons/mirrorrorrim-mod-2019-v-2. The file will be found in the Assets/Model portion of the download as follows: RBellerophon CL, however, you'll notice on the screen shot it has been customized for this mod and will have the Terran Federated Republic banner and accompanied images on the ship. You can remove the customization or create your own by using the modeling tools found here:
https://www.moddb.com/mods/sfciii-mirrorrorrim-v-10/downloads/sfc-game-modding-programs Note: Both models have been sized to their class sizes for these mods and have had the phaser and photon torpedo arcs matched correctly to their intended graphics on the hull. If you use the arc assignment program provided on the modding tools download, you'll see where we assigned phaser and photon torpedoes and the number of each. If you want to add more than provided, you'll need to modify the wire frame model (tool for this is also with that download). Note, adding more firing arcs other than what we assigned, could cause an exception error or not show up properly in the game, so you'll need adjust the customization with the provided tools.