Edelbrock Performer Series Carburetor Calibration Kit # ED1488 Rate_12 Chrysler Small Block LA Proform Chrysler Small Block LA Proform Soft Conforming Aluminum Header Gaskets # 67929 CHEVROLET BLAZER 1973 1991 CHEVROLET C10 PICKUP 1973 1986 CHEVROLET C10 SUBURBAN 1973 1986 CHEVROLET G10 1973 1995 CHEVROLET G20 1971 1995 CHEVROLET K5 BLAZER 1975 1984 CHEVROLET R10 SUBURBAN 1987 1988 CHEVROLET R1500 SUBURBAN 1989 1991 GMC C15 PICKUP 1975 1978 GMC C15 SUBURBAN 1975 1978 GMC C15 C1500 PICKUP 1973 1974 GMC C15 C1500 SUBURBAN 1973 1974 GMC C1500 PICKUP 1979 1986 GMC C1500 SUBURBAN 1979 1986 GMC R1500 SUBURBAN 1987 1991 That's why they offer these calibration kits for Performers series carburetors for Use On Edelbrock 1409 Performer Series Carburetor