This is how I'm going to do it if I end up doing a magnum swap for my Duster. I want it to look as much like an LA as possible. You may already know this, but the 5.9 magnum has a balance that is different than the LA 360. Several companies sell balancers with bolt on weights to match the specific engine.
DODGE Professional Products 80012 Professional Products PowerForce Harmonic Dampers | Summit Racing