The door is exactly the same thickness as the original. This I was surprised about. I will not consider ripping out the jamb. It is original to the house and should stay. Also, I don't understand how ripping out the original jamb and inserting the prehung door will solve the problem. The wall is out of plumb as well. Thanks anyway, but I will probably need to go over to the Old House Journal and consult with those who are used to doing these repairs while keeping the integrity of the house. I'm not interested in "remuddling" the house.