I had same problem about matching 3D loader with patient drive overlay.
I found the solution and i made a video:
https://youtu.be/P2Fcr71LUqsMatching the first 2 letters of s/n isn't enough, you need to match overlays date.
In the video i show how to do that.
P.S:
Overlays date might be found on different offsets, depending on model hard drive.
In my case it was a ST2000LM007.
You just need to seek overlay date with search function in the hex editor.