I already have this file:
I just realized that the mapset of the file I have is exactly like the file here: new-maps-f88/city-navigator-north-america-2017-t18771.html
except for the ending. .20/.30.
I then found this: post79939.html#p79939
so maybe I could take the file I have, rename it to gmapsupp.img and place it in X:\Garmin and it work. The file I have came from a Nuvi 52 that I had updated. I found a unlocker which I used on the map file.