For 1901R 4MV; Rochester Quadrajet Carburetor. Venturi(Choke tube):28mm. Divorced Choke. For GMC 1967-1968 V8 Chevy small block Gen I 5.4L/327. For GMC 1968-1969 V8 Chevy big block Mark IV 6.5L/396. For GMC 1971-1972 V8 Chevy big block Mark IV 6.6L/402.
