I remember walking and talking through with the machinist telling me cast crank, but I may be incorrect. I'm going to call the shop tomorrow and jog memory here. Rotating assembly turned at the machine shop, not with either of the balancers I have.
4 speed. Its possible that the dart the motor came out of before i bought it was an automatic. Don't have that answer.
The balancer i have on it currently was from my 318. Summit OE replacement. Internally balanced motor.
The picture is the balancer that came with the 340 when I bought it.
Here is the item I currently have on the new motor.
View attachment 1716458790