Internally Balance Cast Crank?

There are at least 3 bell-ringers SBM cranks; the 273s,the teeners, and the 340s.
The 340 cranks are the heaviest at around 55#,IIRC
The 273s are skinny little things.You can't mistake them.
The teeners I forget their weight, but they also don't seem to have as many holes as the 340s nor are they drilled as deep. They might be around 50#IDK