The design of the Morris Minors was pretty advance for it's day and used stressed panels instead of the 'ladder' frame of contemporary cars. This created a lighter and stronger car, but when the rust gets serious that strength goes away and we need to replace these panels to be safe. If your doors are wandering all over the place, this is the panel that the hinges fasten to. If in doubt replace it. CHS118 is for the left side.