▁cub ic - inch ▁Ro cket ▁V 8 ▁borrow ed ▁from ▁the ▁Old s ▁ 4 4 2 ▁along ▁with ▁the ▁cut out ▁rear ▁b um per ▁and ▁exhaust ▁tr ump ets , ▁ 4 4 2 ' s ▁r ally e ▁susp ension ▁( optional ), ▁distinct ive ▁S X ▁bad ges ▁and ▁other ▁features . ▁ ▁A ▁W 3 1 ▁option ▁added ▁distinct ive ▁stri pes ▁and ▁bad ging , ▁and ▁a ▁cam sh aft ▁with ▁increased ▁lift ▁and ▁duration ▁for ▁the ▁ 3 5 0 ▁engine . ▁The ▁W 3 1 ▁option ▁was ▁offered ▁on ▁Supreme ▁coup es ▁only ▁in ▁ 1 9 6 8 , ▁but ▁continued ▁on ▁lower - line ▁F - 8 5 ▁and ▁C ut lass ▁S ▁coup es ▁through ▁ 1 9 7 0 . ▁▁ 1 9 7 2 ▁was ▁the ▁only ▁year ▁in ▁which ▁the ▁C ut lass ▁Supreme ▁not ch back ▁hard top ▁could ▁be ▁equ ipped ▁with ▁the ▁L 7 5 ▁ 4 5 5 ▁and ▁M 2 0 ▁four ▁speed ▁transmission , ▁and ▁only ▁ 7 7 ▁of ▁these ▁cars ▁were ▁produced . ▁All ▁ 1 9 7 2 ▁L 7 5 ▁ 4 5 5 / M 2 0 ▁cars ▁used ▁the ▁larger ▁ 2 . 0 7 ▁val ves ▁and ▁the ▁W 3 0 ▁automatic ▁cam sh aft . ▁This ▁gave ▁the ▁L 7 5 ▁ 4 5 5 / M 2 0 ▁cars ▁ 2 7 0 ▁net ▁horse power , ▁as ▁opposed ▁to ▁the ▁TH 4