sure that's not the Defrost Drain Tube ?
...would also need the Water Valve and wiring
I went back and looked at the parts breakdown again and I am 100% sure the parts diagram I am looking at shows an icemaker fill tube as well as an icemaker receptacle (the plug I referred to). However it doesn’t show an icemaker but this isn’t unusual because some of the models that didn’t come from the factory with an icemaker don’t show the icemaker on the parts breakdown. Not that I have seen everything but I have never seen one with a receptacle and a fill tube that wouldn’t accept an icemaker kit (even if it doesn’t show one on the parts diagram).
Assuming the parts diagram is accurate, the only question is if the refrigerator was made when they were still using the round cube icemakers or if it will take the half moon icemaker (IM6). I believe I have actually replaced some of the round cube icemakers with the IM6 kit but it all depends on the type plug.
If you find the plug can you post a picture of it?