I posted this over at Camaros.net, but unfortunately haven't received any responses.
Hopefully someone here can help me.
JohnZ, I understand you have an OE unit. A search brought up text, but none of the pictures you posted.I have this rear window defogger for my 69..
This is how I received it when I bought it maybe 15 years ago.
It shows the ground strap fastened under one of the vent mounting screws.
Does anyone know if this is this correct? Reason I ask is because with the painted surfaces of the defogger housing and parcel shelf, the ground is very poor if any electrical connection at all to the body.
Unfortunately the AIM C50 chapter only shows the switch installation, and the Fisher Body Manual shows nothing. (I'm hoping I overlooked it somewhere.)
Going by clues of the type of serrated keps-nut (nut with integral star washer) that fastens the ground wire, which also has a serrated eyelet, I expect that these are incompatible with each other and the defogger should be positively grounded elsewhere. (or is that negatively grounded elswhere? ) I don't see the point of grounding to the housing of the defogger when it's not making a contact to the body.