VEry good spot... but if you are referring to the Eternal Wrath from OaAI, the book lists thats as being an SFS Ship, not a KDY.
Now thats possible an error on its own.
But very good spot still...
Strangely that's the Wookiepedia line on it too. I assume the reason is the gravity well projector is an SFS creation, and SFS buy in hulls from KDY to produce the Interdictor. There's plenty of cases where different car companies share a chassis but produce different cars under their own brands.

