how to id cast crank 340 flywheel

I have had them switched before and when you use a weighted flywheel for a cast crank on a forged internal balanced engine you shouldn't feel any vibrations or anything odd even though its not really right.

if you use a non weighted flywheel made for internal balance engine on a cast crank external balanced engine...it will be fine up to around 2000 RPMs and then it will vibrate like crazy ....when I did it ...it felt like it was going to vibrate the radio out of the dash .....scary stuff LOL

I understand why you want to properly ID though.