340 Identification.

With the block date code of '72, and the balance weight added to the torque converter.

I am going to say that it is that year specific externally balanced 340. The external balancer for the 340 has a little less weight on it than the external balancers for the 360s.

Looks like the last engine rebuilder put a neutral balance 318/340 balancer on it, maybe not knowing the difference, maybe liked the looks of it better, maybe trying to pass off the engine as a forged crank nuetral balance, when in reality it is a cast crank external balance.

Anyway if it was a neutral balance 340 crank, there should not be that extra weight on the torque converter to go with the external balanced engines. So things are miss matched there.