Flywheel and bellhousing

FACTORY 5.9 magnum flywheels only came in 143 tooth, 11" clutch configurations for trucks. They will NOT fit an A body bell housing.
Aftermarket 130 tooth flywheels for the 5.9 are available to fit A body bellhousings that use the 10 1/2" clutch. HOWEVER, if you are trying to use the factory magnum fuel injection (you didn't say), you need a flywheel with the 8 triggers for the crank sensor. Most I have seen do not have these, and are intended for carbureted applications. The one I do know of that is compatible with injected 5.9s is this one: SCIENCE FRICTION Billet Steel Flywheel, SFI Quality, 130t/10.5", 360 Magnum, 6-bolt - American Powertrain
The rest, as far as I know, are for carbureted 5.9s.