All of the parts are all internally balanced parts in a different combination. There was no balance of the rotating assembly done. Where would the balance issue come from? 273 crank and rods are internal. Fairbanks 3500 converter is a zero balance for a 340. Flex plate is a zero balance part also. Granted using the 273 rods creates a lighter bob weight but that is evenly distributed over all eight journals. If there is something I'm missing here someone set me straight before I re-install the crank.