I have just broken a 3 point lock on my external door , and everybody that I have contacted so far tells me that I have to replace the old one with the same as I had or just put a regular yale lock on . To fit a 5 point lock would mean changing the door, as the mortice holes would be in the wrong place,and some of the faceplate width'es are different on new locks than on the older ones . Hope this was of some use to you.
aikon53
January 2010