AEROFLOW HOLDEN/GM LS WATER CROSS BLANK - AF64-2183BLKSuit GM LS Series Engines, Sold Individually Aeroflow Performance steam vent block off plugs are specifically designed for the GM LS series engine, these cross over adapters will allow you to delete or block off the water cross over tubes on the factory or aftermarket cylinder heads. The low profile design gives extra clearance and does not require removal of the block off when removing the cylinder head bolts. Available in both silver and black