# Adding a rear window defogger



## Omni (Jul 7, 2016)

Good Day and hope that all had a wonderful Christmas

Project GTO ('66 factory tri-power 4 speed) is still underway. Since I have the interior almost gutted I thought about adding a rear window defogger. I have a line on several of the parts but what I cannot find is how the switch is installed on the dash. Are there any pics out there that cover this? My factory shop and parts manual are pretty vague.

Thanks to all who respond.
Omni


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## GTOJUNIOR (Aug 7, 2011)

IIRC Looking at the upper portion of the dash bezel there should be factory guide marks as to where to drill holes for accessory switches.
The factory location for the rear defogger switch is between the far left and second from left gauge pod.

























The power lead runs along the trans tunnel on the passenger side, then up and under the rear seat.
There is a factory wire shield used under the seating area.










































It's always been my understanding that the grille was color-matched to the interior.


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## Omni (Jul 7, 2016)

Good Evening and Thank You for the prompt reply. 

If I understand this correctly, the 'guide marks' are on the top of the dash housing (plastic), which means that the dash needs to be removed to mount the switch. Is that correct?

Omni


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## GTOJUNIOR (Aug 7, 2011)

Correct. No other way. I assumed yours was out when you said the interior was gutted. Anyhow if you look at the upper portion there may be factory guide marks.
Even if you do not find/see any the Switch Bezel can be used as a Template. There needs to be a hole drilled for the threaded switch portion as well as a small indent/hole for the anti-spin tab/pin on the switch bezel. Looking at this file image you can see where this dash was drilled for the speaker switch. Also, note the raised portion of the top of the dash bezel this can be used as a guide for the top edge of the switch. Once you have the layout marked I would double-check it sets in just behind the dash pad before you commit to drilling.
Hope this makes sense.
Cheers.


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## Omni (Jul 7, 2016)

Thank You GTO Junior for the narrative and the pictures - very helpful,
One more question: Is there any specs out there as to where on the package shelf it is mounted?
It appears that it is mounted on the left (drivers) side in the speaker opening. Just looking for some dimensions to correctly place the grille.

Thanks to all who respond.

Omni


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## GTOJUNIOR (Aug 7, 2011)

The factory package shelf used in '66 only had 1 provision for a single speaker at the center of the shelf.
As you have noted the RWD is installed just behind the driver. There are two factory holes punched for this.
Looking at the plastic deflector you will see a square and round hole. These correlate with the shelf cutouts.
There are also 3 small holes to place the grill studs down through. The package shelf shown is aftermarket and would be looking up from inside the trunk.
But gives you the idea.


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## Omni (Jul 7, 2016)

Thanks
I finally was able to look up from the back seat area and saw the template in the package tray. 
looks very straight foward from here.

Thanks again for all the pics and descriptions.

Omni


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