That flush mounted headlights were nixed at the last moment (by FoMoCo) because there was a hang up in the Gov't over them being "legal" And yes that said Gov't is the opposite of "progress".
Well, Congress, anyway. Those dolts were dickering back then to the wee hours about everything that year.
I owned an 84 for 22.5 years. I can't say that I miss it, but it was a love hate relationship. The guy I sold it to, put a huge turbo on it and put a hole in the block and parted it out. He had it for 4 months.