37 Plymouth coupe heat help

I bought a 37 coupe that I am fixing a few odds and ends on before I give it to my father. I have gone thru the heater and the got everything connected. The hose that is connected is fine but I can't figure out where the other end goes. Probably easy for you guys but i am stumped.

You can see where the other hose would hook up at the firewall but there is no connection that I can find for the other end of the hose.

If one hose is connected at the back of the head, the other needs to be connected at, near, or to the water pump. Is there a pipe plug somewhere around there?
Bryce

Really crawled up in there and up underneath that short piece of rubber hose is a plug. Off to see if I can find an inlet tube. Thanks Bryce.