340 engine (flywheel)
As HemiSSDart said, you need to look at your harmonic balancer, if it's a cast crank with this balancer, it's externally balanced:
If it's a forged crank, it is internally balanced and uses this balancer:
If it's externally balanced, you need the specific 340 cast crank flywheel, but not the externally balanced LA 360 or Magnum 5.9 flywheel, which are all different.
If internally balanced, any of the internally balanced flywheels will work.
And technically, it's not a matter of "balanced" or "unbalanced"- they're all "balanced", just balanced differently; internally or externally.
As HemiSSDart said, you need to look at your harmonic balancer, if it's a cast crank with this balancer, it's externally balanced:
If it's a forged crank, it is internally balanced and uses this balancer:
If it's externally balanced, you need the specific 340 cast crank flywheel, but not the externally balanced LA 360 or Magnum 5.9 flywheel, which are all different.
If internally balanced, any of the internally balanced flywheels will work.