The first digit identifies lower body color
" 1 " identified special paint, as opposed to an alpha code standard color
"-" is just a spacer
IF it would have had a White Vinyl Top, it would display 1-1
like the trim tag sample i posted earlier in thread [ 1-1 ]
Which was also a Pontiac Plant A-Body
IF it would have had a White Painted Roof [two-tone]
it would display 1-C
No real need for the spacer [ - ] On This Car , but they included it anyway.
And this explanation should only be applied to a 1968 Pontiac Plant Special Paint A-body , to keep things simple.
Not all plants used a dash/spacer
Here is an Arlington Plant , 1968 Carnival Red with White Vinyl Top trim tag. [ 11 ]
No dash/spacer
Can also note there is no Vinyl Top option listed on the Window Sticker for the Windward Blue car. fwiw