SFM6S1825 GT350H on auction - Automatic, 148K miles

[J_Speegle]

I wonder what that big hole to the left of the wiper switch is?

Likely for a switch for some purpose. Not unusual to find one added to a Shelby or any other hot rod of the period. If the switch is gone, along with the wiring it will be difficult to figure out why but there may be a clue somewhere under the dash