Jess. Maybe this will help. Look at the pic of the HX found here. Scroll down to the HX only pic.
http://www.moyermarine.com/cgi-bin/s...rebuilder.html
I am not at my boat but I believe that the antifreeze hose from the exit of the manifold enters the HX at the fitting closest to the cap. The fitting at the lowest point of the HX is for the hose that returns the antifreeze to the FW pump. The two fitting close to each other are for the RW. I do not think it matters which is in and which is out. I used the right hand fitting to enter and the left fitting to exit. Again I am working from memory so maybe someone can confirm this info.
Dan S/V Marian Claire