They are Mustang lamps with the crossbar removed, but they will work and fit as the originals do.
(housing, bezel & bulb are the same shape).
There is a difference between mid-60s/late-60s Mustang fogs as to where the stud comes out of the housing - one is in the same location as 'Cuda, one type is off.
Technically, there are a bunch of small differences as well, right down to the type of rivet holding in the stud mount as well as the aforementioned Pentastar.
Wires for Mopar are black & blue, and the wires are separated as they come through the grommet. Mustang lights are black, and more like lamp cord.
Bulb type is a #4415 sealed beam. Either GE 4415, 4415A (amber) or Westinghouse 4415s are assembly line correct. GE bulbs will have 'FOG' just above the 6 o'clock position. Westinghouse will have the 'W' in the centre of the lens.
There are many 'NOS' bulbs in Chrysler boxes - they will work, but they're not correct. They are made by Wagner and can be identified by a 'ts' logo at the centre of the lens (Tung-Sol)
For $100 and they're local? You can't go wrong.