I recently purchased a beautiful 63 Riviera sight unseen without an HVAC system. It was Hemmings Find of the Day in Feb 2021. The body, interior, paint and drivetrain were all beautiful, so I just assumed that one of the prior owners was an idiot for tearing out the heating and a/c system, and bought it anyway. Upon further inspection I saw that the firewall delete plate was very well done. It fit well, was beaded well, and installed well. I can live without a/c but need a heater as I live north of Chicago, so I installed a Vintage Air heating unit and moved on. I recently entered a local all Buick car show (and took best of show) where I met several very knowledgeable Buick guys who suggested the car may be one of a hundred or so "heater delete" cars on record originally purchased in southern states. Note that this car was originally purchased in southern California. Any insight or ways to prove or disprove this theory would be greatly appreciated!