I can't speak for A-bodies, but B-body white interiors (except Charger) had different white treatments in '68 vs '69.
The '69 UDF colors for white interiors were most often white, where in '68 they were the contrasting color.
While '68-'69 A & B cars appear largely similar, the colors and treatments differed.
The Dart color & trim selector at Hamtramck-Historical unfortunately doesn't mention UDF color, only contrasting carpet, which matched dash.