I have an older analog TV that I want to use in my garage just to get local channels. With FIOS do I need a set top box or can I just plug my coax cable into the TV to get limited channels?
I don't know. I'd tell you to buy a digital tv converter box, but it sounds like you already have FIOS service and a set top box.
You need some kind of box. The signals are Digital now (OTA or FIOS).