Getting GameObjects with same Prefab?

Hello, I have an instanciated prefab in the scene, and I would like to have a script attached to him that finds all of the other GameObjects in the scene that are also instances of the same prefab. Normally this would be easy, but the kicker is that I can't use tags, layers, names, or script references. The common ground has to truly be, the same prefab. Is this even possible? Thanks ahead of time.

By not using names, you mean not using the names of the game object?

But anyways, what I could think of off hand...

Make them children, and have a "Master" object, then just get all the children...

Any reason in particular you can't use tags? You can have more than 1 tag per an object...