Estate benneficiary dies. Does his chid have claim to his share of the estate?

My Grandfather died without will and with everything in his name. I am told that the property is now an estate and must be divided to hi wife (my grandmother- living) and three children (my Dad just died and his sisters- living). My dad just passed away and I am wondering if I have any claim to his share of the estate? I am an only child.

He also put his truck in my grandmothers name when he became ill (I was not aware of this) and I would like to take possesion of the truck, I know he paid for it. Do I have anything to stand on in this situation?