I have a 143 tooth flywheel. I have tried to run the numbers. how can I tell if it is for netural balance of external. Or will I have to take it to a machine shop. I don't even know where it came from. Any help would be appreciated. Cliff

Are there weights or drill holes on the backside?

...well, wait. Weights would be a sure sign of external balance... I suppose a neutral balance could still have holes drilled on it to correct it back to neutral.

No numbers anywhere? Safest bet is to have someone soon it to test it and see if its neutral or not

Pictures! We must have pictures!
R.

The casting number on the flywheel is useless for ID because the same basic casting can be drilled for external balance or not. IOW, the part number changes but the casting number doesn't.

One or two small holes is an indication of zero balance or internal balance. On the crankshaft side of the flywheel, if I remember correctly, mopar machines part of the material away. It'll be a fairly significant amount. If you have some way of putting it on some V blocks, an external flywheel should self align itself with the weight to the bottom. Whatever mandrel you use needs to fit the center of the flywheel pretty tight, it can't be sloppy.