How can you identify a 340 motor

273/318 have different driverside motor mount ears than 340/360; 4 lugs versus 3 on the smaller engines.

EDIT
I think it's the drivers side. In any case, the 340/360s have 4-lugs on both sides
whereas the 273/318s have only 3 lugs on one side and 4 on the other.