when we pulled my engine out I didn't take note to which heater core line went to which side. The guy who finished the job has the water pump going to the (when looking from the front of the vehicle) left side and the manifold going to the right side. I do not believe that is correct. Can anyone shed some light on this? I couldn't find anything definitive online.

 

You are correct, they're backwards. It doesn't matter as far as functionality of the heater core, but it may make a difference in routing the hoses.