Floor brackets under AC vents?

[RabidScott]

I have these two factory-looking brackets on the Dart located on the hump under the plastic AC manifold.

The PO screwed a tach into one of them.

What are these for? There's no other brackets or hole for a floor shifter.

 

[MoparMike1974]

What year dart? Could have been for a buddy seat.

 

[RabidScott]

Its a '74 Dart 2 door SE.

They're under the dash on the hump so it seems unlikely they're for a buddy seat.