Quadrajet id codes
Listed here are the ID codes for the quadrajet carburettor and jet sizes, metering rods and hanger sizes
601 = Pre-Pollution-HT to Early HJ - Red Motor
602 = Semi-Pollution - Late HJ to VB - Red Motor
603 = Post-Pollution - WB/VC to VK(?) - Blue Motor/black motor
Also the 253 quadrajet were jetted differently to the 308 quaddies.