Restoring A/C Heater box under dash

Detroit Muscle has great kits for this.

I used a wipe on fiberglass resto product made for boats after a good wash on the box. It turned out pretty nice. The color popped right back as it once looked.

Just be careful puttting the clips back on the box. Don’t force them and use a flat blade screw driver as a lever to hook over the clips and set them or get a set of speading wide bill snap ring pliers or similar for re-assembly. Do not try to pop them back on with a mallet or such or you will likely cause damage to the case.