Not sure of the model numbers but cartridges in many of these old Deltas are almost not replaceable as they are made in 2 parts with the fore part connected to the main body with small delicate copper tubes. If you torque the cartridge it will likely just break these tubes off. I was going to repair my parents' old Delta but luckily I inquired before I put any real torque on it. The plumbers solution to this situation if you don't have an access panel is to cut out a big enough opening around the valve to cut it out and replace the entire thing. Then use an oversize trim ring to cover the opening. Of course if the surround is tile you can remove the tiles, do the replace, then re-tile.