Designed for street 396-502 c.i.d. big-block Chevy V8s using general duty oval-port cylinder heads. #2161 is stock replacement/street legal part for 396, 402, 427 and 454 V8s with OEM 4-bbl. carb.; 1965-72 (1973 non-CA) passenger cars and 1966-83 trucks, Suburbans and heavy vehicles; except stock equipped EGR. #3761 is stock replacement/street legal part for 454 V8s with OEM 4-bbl. carb.; 1972-89. Will not fit under hood of Corvette without hood modifications. Will not fit “tall block” V8s. May be used with OEM or aftermarket carbs. Will fit 1965-90 oval port heads. Available with standard finish, polished or with new PermaStar finish for a look you’ve got to see to believe.