Factory heater delete
LOL. You were only supposed to order them where you didn't NEED a defroster
My old friend, RIP when I was in San Diego used to tell me stories of his 53 Chev that was factory no defrost. But I spend a winter with a leaking heater core (disconnected) in my 63 Chev and I can tell you that was an ucomfortable winter!!! It gets cold enough to need heat down there, and in fog or rain, you DO wish you had a "defroster!!"
NAS Miramar, about 1970