Hi - yes, I used OSM on my Quests for several years until the data density meant that the Quest’s 243mb could only handle limited areas at a time. This quest (small Q!) is on behalf of some prehistoric mates who, understandably, find the device sufficient for navigation needs
Anyway, Map ID 379 looks the closest so we will see if that mapset, Mapsource and the Quests are in alignment - something that I believe is called a syzygy ...