I did it today. Opened the box from Tivo. 4 screws to get the cover off. Unplug the drive. 4 screws to take the drive out. 4 screws to take the side rails off the old drive. Put the side rails on the new drive, screw the drive into the chassis, plug it in and button up the cover. Hook it up, go through guided setup, reboot a few times, boom. Working Tivo.