I’m in the process of changing doors in my sisters house.  The house was build around 1950 on Long Island.  It was common back then for new construction to use metal interior door frames.  They were nailed to the frame with metal tabs and to the subfloor.  The finish flooring was nailed over the subfloor tabs.  As far as I can see, the only way to replace them is to take up the finish flooring if it runs parallel to the door or to cut a piece out of the floor if the floor is laid perpendicular to the door.  Has anyone found an easier way?  It takes longer to remove the old frame and repair the floor than it takes to install the new door.