Moemoe,
Nice job on the grapple. One more little addition you might want to think about is adding a brace to the bracket holding the back of the ram. Maybe you already have one on there, I couldn't see the back from the pictures you posted. I found with the one I had built that there is a lot of stress in that area. I just broke mine. I was picking and loading wood. The height of the rear bracket leaves it prone to problems. A quick brace will do the trick for you.