Well it doesn’t actually have a heater so I’m not sure what it’s called. I’ve been told that GT’s are supposed to have heaters but mine doesn’t. Not surprising given the questionable quality control from the factory back then. Hard to believe that heaters were an optional extra back in the 60’s! Anyway, mine is in pretty good nick and the rubbers and mechanisms all good. There is a little bit of surface rust on the inside but I resisted the urge to strip it back completely to sandblast everything as this would have meant disassembling all the moving parts with no guarantee that it would go back together as well. And it’s all hidden behind the dash. So with that in mind I pulled all the main parts off it, gave a light sand to everything I could reach and a coat of paint.