that's a neat old radio, i have one sorta like it, but not exactly the same.
i can tell you the "PB high" probibly has a weather band station (the "wb" in the rectangle). i think "PB" might stand for public bullitin? not sure though.
then the "MB & SW" could possibly be a manual police / CB scanner. i'm not sure on that though, but i know mine's got a feature like that, and the numbers on youre's look like they could be CB channels?
here's a pic of the one i've got, the differant selections on the one i've got are FM, AM, SW, VHF hi (with weather band) VHF lo, and UHF. if i remember, the SW is basically a police scanner that you manually tune.
i don't know about you, but i can listen to the park ranger chatter from my house, about 5 - 10 miles up the mountian from the park land where they are
the weather band is good too for if you're power goes out. assuming youre's is battery powered like mine.