Designed for street 429/460 c.i.d. Ford V8s. #2166 is stock replacement/street legal part for 429 & 460 V8s with OEM 4-bbl. carburetor with electric choke; 1968-72 (1973 non-CA); except stock equipped EGR. #3766 is stock replacement/street legal part for 460 V8s with OEM 4V carburetor with electric choke; 1979-87. Will not fit 429 Cobra-Jets or 1966-68 462 Lincolns and will not accept stock spread-bore carb. Will not fit 1988 and later models. #3766 cannot use #8714 to block-off EGR. Must use stock EGR plate