The storm door was made by HMI storm doors which does not appear to be in existence any more.
The company that installed the door also does not appear to be in existence. Easter's Locks suggested that I reach out to you. There are no markings in the door latch. The rest of the door is fine and I can easily install this door latch. As you can see in the photo, there is a square hole on the inside of the latch, that fits perfectly into the "stem" on the front handle. The screw holes are one and 3/4 inches apart.