That engine is out of a rather large track-type earthmover; it's about 3 times the size of one from a full size pickup. The grappler is about 4' tall. Yes, even the seat is about the height of the roof of the mobile home there.
I have no idea what that big metal box was, but it's gone to the recycler now. Many, many tons of steel have gone to the recycler in the last few weeks. It's very nice to know someone with a giant machine who can deal with the stuff rather than trying to load it by hand! It's sort of like a giant version of one of those games where you put a quarter in and try and grab out a stuffed toy. Must manage to convince the owner to let me play with it one of these days!