Chevy has gone full circle on this deal. My 93 vette has the following configuration. There is no balancer like you think of a balancer, there is a crank hub that is not keyed to the crank, there is a pulley that bolts to that and there are no timing marks. You talk about a weird deal.
If you step on the motor and start to make some serious power, say 400hp, the crank hub starts to creep or rotate on the nose of the crank!