Older Milgard casement window locks

Start by looking at our 38-095, 38-096, 38-138 or 38-139 Multi-Point Locks. Compare all their dimensions, especially the projection of the fork, to your old lock and see if any of these match what you need. 

Without seeing the lock actually removed from the window so the rear can be seen, there's no way to narrow this down further. See the video below that shows how to remove and replace these type of locks. Note that if the lock does have a fork projection like the four possibilities I mentioned, then I believe one of these will still be the closest match, and it will come down to dimensions.