For 1968, column shift was standard for auto trans, floor shift was the option. It was standard on the base model cars with manuals also. So, not unusual to see it. Note all this is for '68.
I think that since so many people(including me on my coupe) have converted these to consoles that the perception of the column shift is that it was unusual.
1968 400 Coupe, verdoro green, black vinyl top, auto 1969 GTO Judge coupe, Carousel Red, manual 1971 Trans Am, cameo white, auto 1970 Buick Skylark Custom Convertible 350-4(driver), Fire Red, white top, auto 1972 Buick GS Stage 1, Royal Blue, black vinyl top, auto
