I did have a 2008 F-250 for a while. There can be a lot of electrical noise going on inside those trucks. Also, the metal roof of a crew cab (don't know if you have that) can be a large shield that blocks signal. Also, certain Fords (not mine) had a metal film on the window glass to reduce heating inside from the sun, which again would form a shield.
So, I recommend an experiments. Move the GPS to a side window of the truck that is open (maybe not the easiest experiment in winter). If that works, then you likely have an issue with the signal being shielded. If that does not work, then we might want to investigate electrical power quality from your truck.
Once you have some results, we can make some recommendations to help out.