Dear mid-60s Buick parts hounds,
Anyone keeping an eye on eBay has probably already spotted this kit, but I had never seen one before. It is an aftermarket kit to install a radio antenna on a 1964-65 Special or Skylark:
https://www.ebay.com/itm/305139442807As the vendor states, you could make it look factory complete by adding the chrome teardrop base plate. It is an interesting item, but it may be somewhat hard to sell. I wonder how many 1964-65 Special or Skylarks still exist that don't have an antenna.
Edouard