My 69 convertible (purportedly) has the original power antenna, and its mast does not fully retract as per the photo of the light blue convertible. I was not surprised to see this, since my '65 Corvette also came with a power antenna (standard with the radio option) and its mast does not fully retract either. A question for someone with an original power antenna, how quickly does it extend/retract? Mine is fairly slow (much slower than the repro I have in the 'Vette), but that may be a lubrication/cleaning or electrical contact issue.
