Trying to get my step dad's '87 GL back to 100% original spec. Thing is, it didn't come with a head unit. Only thing to go are the wheels back to GL steelies and finding the standard, original head unit to fit. Anybody got any idea what head unit was fitted to this car from the factory. Take it, it's going to be a Blaupunkt? Just need to know what model number. Any ideas?