I'm still using my Garmin original Streetpilot circa 1998. I have topo maps and streets. Streets are getting a bit outdated but there is info on how to modify maps manually. Maybe someone will publish some eventually.
It runs on up to 48 volts too. It's waterproof and so far dust proof. BTW, I've needed its waterproof aspect already. You may have seen my water post pics.
Someday I guess I'll need to change but with a Pinz I don't worry about roads!
Sorry, I've been no help on this thread.
Oh, because it is wired directly into the 24 volt side it's a great volt meter! You can put it into diagnostic mode and it will tell you what it's input voltage is!
If you didn't get stuck, you didn't try hard enough.
'74 710K
1984 in 2009