In Germany, I do remember being able to hear a tracked vehicle coming a lot easier due to the squeaking of the tracks than a wheeled vehicle so there may actually be some merit to "anti-squeak" use. I could see a rock or something coming up and hitting that panel. Rather than giving a gong ring it might muffle it enough to shorten the distance the sound carries.
I don't recall ever seeing an MWO on anti-squeak. It is in the '54 ORD 9 parts manual, the second edition of the manual (superseding the '51 edition) since the truck was introduced so I doubt it was an MWO. rboltz's truck has them and it is a '52 so I'm thinking they are part of the original design.
I find myself preferring the older manuals as I restore my truck. They describe the hardware in detail (size, finish, pitch, material, etc.) rather than the later series which just say "screw" leaving you to figure out what characteristics it had. I do admit that I have spent quite a bit of time looking for something that isn't called out on the IPB but I've learned a bit about these trucks doing that.