I am in the process of replacing the intake gasket on my 1989 TBI 4.3 that is in my buggy. The new gasket set has both water passages on the rear of the heads blocked. When I pulled the intake the existing gasket appears to only have one of the water passages blocked. Both rear passages cannot be block because the heater hose attaches to that passage in the intake. Having just one passage blocked does not make sense to me either as there would be no cross flow. Can anyone clarify how this should be? Thank you very much for your help.