Rubber seal?

[bcstingray]

I replaced my heater core in my 73 today. I noticed when I replaced the inside heater box that there was a gap between the heater box and defroster duct work. Is there supposed to be a rubber seal between the two? When I removed it, I did not see anything on top the box.

Also, just want to make sure that the 3/4" hose goes to the water pump and the 5/8" hose goes to the intake. I have heat only on this truck.

My truck originally had a 250 6 Cylinder, now has a 357 V8.