New heater core was installed. I purchased heat-resistant foam tape to secure the core (arrows). An oval indicates the end of flap, which should be inserted into a hole in the upper housing.
The heater core was supported by this unique shape plastic part.
Place the upper housing trying to insert the flap end to small hole in the upper housing (oval). This might needs some patience since you can't adjust the position of flap end from the top. The other end of flap protrude from lower housing and you can test if it moves smoothly by turning it with your fingers. Once you succeeded to close the unit completely, put all the 13 screws back.
Adjust the position of heater line so that you can secure it with a screw (oval).
Put some glue to reattach the foam to the upper housing. Don't forget to embed harness in the slit first.
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