That is not going to be as easy as you might hope it would be.
I don't know your starting point (if you maybe already know which 3d model file is used or not)... but let's just assume you know (I don't).
In shiparch.ini you will find all ship definitions including stats. There you can search for the file name of the 3d model to find the nickname of the ship_archetype.
Before you shout "hurray"... you can not use it for editing a savegame (I assume that is what you want to do).
Instead you have to figure out if this ship nickname has been used to create a playable ship already. If so you can find the nickname from the shiparch.ini somewhere in the goods.ini labled as a ship package. Copy this ship package name... and search for it in the same goods.ini file. You should find a ship definition with a loadout (engines, powerplant, etc) then. The nickname of this ship definition is what you need for your savegame.
However, in order to use it in the savegame you will have to convert it to a crc using FLdev or CRCtoolkit or probably a million other tools able to do that task.