You will either need to glue it on, or get the buttons/retainers for the earlier model cars to install it. Some folks have simply glued on the foil insulation normally used on interiors, under the carpet. Works quite well.
You might be able to use the factory style insulation panel for an earlier car with no problems, but the shape of the hood is different, so a molded panel might not fit as well as a flat, or non-molded one.
Mid-Am does have the correct style
Replacement panel, as well as the retainers. The one they are showing would not be correct for the '78, tho, so ya might wanna ask them when ordering if they do have the solid type, without the opening in the center.
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