On the drivers side of the carb you will see a vertical small pad with stamped numbers, may begin with 70, roughly 8 digits. The small bores face the front of the engine, drivers side will have throttle lever and secondary linkage. Chevrolet used a side fuel inlet on the top right, Oldsmobile used a top front center fuel inlet.

1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy