From the time when the '68 cars were new, until last May, every original 4-lamp B-body I've seen had General Electric (spelled out) sealed beams.
That's hundreds, if not thousands, of them over 50+ years.
Last May, as some here may recall, I bought a 17,000-mile original '69RR. It has Tung-Sol low-beams. St. Louis car, SPD 2/12/69.
I was surprised by that, but pretty sure it was built that way just based on mileage.
I can't confirm unless I pull them and check dates, though that may not be conclusive.
Such a unique & odd experience for me, I'll probably leave it that way, though my OCD prefers all 4 from the same manufacturer.