heater hose connection
I cant speak to a 74 (Assumption as no engine or vehicle listed in the post) But looking at the heater core and diagram on my 67 273, as other have spoken about... the drivers side heater core tube goes to the top of the core and the passenger side goes to the bottom of the core
The diagram below shows the hot water from the manifold going to the passenger side tube to the bottom of the core and the return to the pump coming from the drivers side tube to the water pump (meaning the water pump connection is on the suction side of the system).
In all the images, in the 67 FSM, the drivers side heater hose always goes the the farthest forward connection (IE water pump)
I cant speak to a 74 (Assumption as no engine or vehicle listed in the post) But looking at the heater core and diagram on my 67 273, as other have spoken about... the drivers side heater core tube goes to the top of the core and the passenger side goes to the bottom of the core
The diagram below shows the hot water from the manifold going to the passenger side tube to the bottom of the core and the return to the pump coming from the drivers side tube to the water pump (meaning the water pump connection is on the suction side of the system).
In all the images, in the 67 FSM, the drivers side heater hose always goes the the farthest forward connection (IE water pump)