Where can I buy the under dash ground piece?

[Axle]

You can also find them under the dash of 80's early 90s fords, if you come across a crown vic or grand marquis with the instrument cluster removed and the trim out of the way, it is to the right of the steering column up a bit, harder to get to than the trucks if everything is there, but an alternative if oppertunity presents itself when looking for a donor vehicle.