A stiff front and mid plate added to mount the engine securely to the chassis. Using the chassis to help eliminate block flex is the best on a LA block. Mount ears on these blocks create stress. Did you ever wonder why 340-360 blocks have a narrower mount on the left side?
Watch a sprint car come off a turn. If you would use mount ears on a mopar sprint car the block it would destroy itself. Many race blocks don't have mount ears. Using both front plates and mid plates help eliminate flex. Most high torque cars use the chassis to stiffen the block.
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