Its a set of pipe clamp forks, but I don't know what it fits to.
It kind of looks like a merlo attachment with the bottom pin, but their side ears on a merlo are more like a loader quick coupler.
Honest answer- the odds of you finding out what exactly it fits to are slim, and its going to be even harder to find that guy that owns one and wants your forks; but it wouldn't be hard for someone to make up adaptors to fit whatever they own. Most of the pipe clamp fork set ups are used on wheel loaders.