Heater Core

Paul King said
^Thank you so much great help .

My Pleasure. There is also a flat rubber gasket that goes between the engine side of the firewall and the metal plate the foam rubber doughnut fits into. And the sleeves go over the firewall studs on the passenger side (I think). You can zoom in on my pre-engine overhaul pic to see the plate and nuts holding it all together.

Good luck!