I had the 4 screws all neat and separated, then accidentally got a super-strong rare earth magnet too close to them, and they were all mixed up. To determine the difference between the 1.3 and 1.2, I pulled out calipers. I found both of mine to be 1.1 mm, so they weren’t different lengths. Also, all 4 of mine were attracted to the magnet.
UPDATE: In response to my question - yes, I was doing it wrong. I just installed the new drive into my MacBook Air, and used Internet recovery to format the new SSD. It worked great.
I differed, though, from the instructions here. The article recommends to use internet recovery to install the OS, and then use super duper to replicate the original (cloned) drive onto the new drive. Except when I went to install the OS using Internet Recovery, it was going to install Catalina, which I don’t want to do. (Catalina doesn’t support Aperture, which is my favorite Apple application). So instead of using internet recover for that, I used Utilities to restore the original drive onto the new drive. It worked perfectly.
I bought the recommended OWC SSD, but mine isn’t recognized by my 2015 (early) MacBook Air 13”. I installed the new drive into an OWC Envoy Pro, with the intent of cloning the original drive onto the new drive, then installing the new drive into the computer, and sticking the original drive into the Envoy Pro. Is this what I’m doing wrong, should I just install the new drive into the computer, and move the original drive into the Envoy Pro?