Lou, as I think I mentioned, our minds generally go right to Matty Ianniello as soon as we hear that nickname. But in this case, "The Horse" was actually E-3, or Frank “The Horse” Buccieri (Chicago)

Frank Buccieri was an old-time veteran soldier of the Chicago Outfit.

I believe he was related to Fiore "FiFi" Bucceri, as either brothers or cousins.

PS: I have a funny story about Buccieri that I'll be posting up at some point for a few laughs.