1968 Plymouth "sunfire yellow" paint code is "S"
1969's "Y2" & 1970's "DY2" is the same color!!

GM's color code "40" used on various cars '65,'67-'69:
Pontiac "mayfair maize" / Chevrolet "butternut yellow" & "crocus" / Oldsmobile "saffron" / Cadillac "colonial yellow" / Buick "cameo cream" & "bamboo"
.... is a similar shade of yellow. However, it does not have the same formula!!