DANGER! That page is WRONG! 1968 thru early 1972 340 motors used forged crankshafts. They were all neutral balanced [crank, harmonic balancer, flexplate, and convertor].
Later in 1972 they put cast iron crankshafts in them. This required a special harmonic balancer with '' for 340 cast crank only'' cast into them. Plus weights added to the front of the convertor to 'offset balance' the entire rotating assembly.
