). ▁The ▁ 4 5 5 ▁Ro cket ▁V 8 ▁was ▁optional ▁through ▁ 1 9 7 6 , ▁and ▁replaced ▁by ▁a ▁smaller ▁ 4 0 3 ▁Ro cket ▁V 8 ▁in ▁ 1 9 7 7 , ▁the ▁same ▁year ▁in ▁which ▁a ▁Bu ick - built ▁ 2 3 1 ▁cub ic - inch ▁V 6 ▁replaced ▁the ▁Che vy ▁inline ▁six ▁as ▁base ▁power ▁in ▁most ▁C ut lass ▁models . ▁ ▁For ▁ 1 9 7 6 , ▁the ▁C ut lass ▁Supreme ▁Br ough am ▁cou pe ▁was ▁added ▁to ▁the ▁line , ▁featuring ▁a ▁more ▁lux ur ious ▁interior ▁trim ▁than ▁the ▁regular ▁Supreme ▁model ▁with ▁pill owed ▁cr ushed ▁vel our ▁u ph ol st ery ▁and ▁ 6 0 / 4 0 ▁ben ch ▁seats ▁similar ▁to ▁the ▁larger ▁Nin ety - E ight ▁Reg ency . ▁It ▁also ▁received ▁quad ▁square ▁head light s . ▁For ▁ 1 9 7 7 , ▁the ▁Br ough am ▁was ▁also ▁available ▁as ▁a ▁four - door ▁Col onna de ▁sedan . ▁The ▁gr ille ▁was ▁also ▁changed , ▁with ▁each ▁half ▁divided ▁into ▁five ▁rather ▁than ▁two ▁segments ▁of ▁bars ▁divided ▁by ▁chrome ▁stri ps . ▁ ▁A ▁five - speed ▁manual ▁transmission ▁was ▁available ▁as ▁an ▁option ▁with ▁the ▁ 2 6 0 ▁V 8 ▁in ▁all ▁models ▁except ▁Supreme ▁Br ough am ▁and ▁station ▁w ag ons ▁for ▁ 1 9 7 6 - 7 7 . ▁ ▁Four th ▁generation ▁( 1