Factory Chevy Big Block High Perf Oil Pumps?
 

Anybody know how Chevy identified there factory oil pumps on there BB high performance engines? Did they tag them or use the casting numbers on the pumps to identify the pump. Seems like there has to be something out there for Oil Pumps. Heads, Blocks, Intakes, Exhaust maniflods all have casting numbers to show what these parts are. Any experts out there to answer my questions, Thank You.