I am about to re-install the heater core and defrost duct in my 67 and was looking at what gaskets I'm going to need. I see they sell a heater core seal kit but are all the gaskets used? The kit comes with gaskets that are supposed to go on the blend doors. Did they use gaskets on these doors back in 67? If so, how do you replace the gaskets? I don't see any old gaskets on my doors now.

Were gaskets used top and bottom of the defrost duct? It's been 13 years since the car was taken apart so I don't know what gaskets are needed. There are no instructions in the kit.

Also, when the body shop installed the outer firewall heater cover, they covered part of the holes. The heater core pipes won't fit through. I'm going to have to remove the fender on a new painted car to align the heater cover.