We carry many different styles of water pump housings for the big block Mopar engine. The largest difference between styles is whether the lower radiator hose is on the drivers or the passengers side. Standard car type (drivers side lower hose) cast iron housings weigh 13.5 pounds while aluminum units weigh 5 pounds, saving you 8.5 pounds by running an aluminum housing. When ordering a water pump housing, don't forget a new water neck and thermostat, both are available separately on our site.