Hmmmm ... some perplexing comments above regarding Nuvi reception in Class C cab areas.
Our previous Nuvi 455T and our current Nuvi 3550LM work perfectly on the dash of our Class C. The 3550LM even picks up satellites inside the house in the office when on the desk near a window.
However in our Class C, when underway, we keep the overhead cab bed stacked/folded up into it's storage position so we can stand up easily to go back to the rear. Hence in this situation the satellite signals only have to penetrate the RV roof - instead of both the RV roof and the cabover bed. I wonder if this has anything to do with Nuvi reception in a Class C cab??