Instrument Voltage Regulator 68 Cuda

While I have my dash on the bench and the Cuda in the shop I decided to upgrade the dash somewhat. The dash it repainted , new top pad , bezel re chromed , gauges cleaned up and needles repainted.
I got a new electronic Instrument Voltage Regulator to install .
After it arrived I see that looks like it wont go into the fuel gauge.
Is there somebody out there that has directions for this upgrade ?
Do I take the gas gauge apart , remove the factory one and re-wire this one externally ?

I'm also thinking about converting the ammeter over to a volt meter..

And what is the piece I have in my hand in the 3rd picture , it has a different connector then the voltage regulator I received ,
But I would have sworn that it was the regulator when I ordered the electronic one ....

Thanks

Donnie

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