Rural route addresses

Well, if you have the coordinates, then you can enter the location with those on the nuvi 350.

But for other locations, if you don't have an actual street address (and an RR address isn't one) and if you don't have coordinates, you won't be able to do it on the unit without some help.

Your options are to browse the map on the unit (if you know the general area) and try to set a point visually, or you can Google search it on your computer and try to search out the lat and long with Google Maps or Google Earth. Or you can physically go to the location (if you are near it) and mark a point. Or call the store and ask them if they know the coordinates.

I have trouble finding any companies with rural route addresses
41.998417, -76.137750
+41° 59' 54.30", -76° 8' 15.90
Those are the co-ordinantes of StateLine Plaza RR1 Box 1025 Little Meadows PA 18830 250 south of the NY/PA line
a free listed WiFi site
with
Outright Sales a Sunoco gasoline, diesel 7 Lp filing station outrightsales.com
Outright Deli, the WiFi site
Skyline Services a PA motor vehicle tag agency
Skyline Insurance skylineinsurance.com
Outright Hardware a hardware store

Without street addresses the GPS becomes very important.
How do I add or find these places?

Of course, my Gramin does sent me through unplowed State roads, though dead ends and other places that anyone who lives here knows best not to travel without survival gear. But that is living in the sticks