Replace a Prefab with another in C#

I thought this would be relatively simple but its not working... Basically, use a slider control to cycle through a bunch of different prefabs that have been assigned in the editor the the script.

public class ChangeModel : MonoBehaviour { // Start is called before the first frame update public List fullModels; public Slider frameSlider; public GameObject previewModel; void Start() {

 }
 // Update is called once per frame
 void Update()
 {
    
 }
 public void ChangeHavocFrame()
 {
     previewModel = fullModels[Convert.ToInt32(frameSlider.value)];

} }

No errors, but the previewModel never changes as the slider changes.

My pre-fabs have several different meshes within them, as well as different box colliders.

Any insight would be appreciated!