Yup, I've seen these. Now where does it go? (inches from side/front)?
Here are pics of my '68 Lemans - had the 3-speed manual transmission. The "shifter porch" is shaped so as to fit where it follows the contour of the driveshaft tunnel. I show the measurements just to give an idea of how it locates. Looks to be 4" from the floor rib to the front of the cover.
I included the front console bracket location if you or anyone else needs to add it. The bolts are not even, they are off set on the bracket with the left one being further down leg. Looks like it is the center slot that the console screw goes into that is actually centered. I measured off from the trans tunnel where it meets the floor and created the flat spot. The distance from that point to the front of the console bracket measured 3 inches. That should get you close enough to attach a console.
The third pick shows the location of the shift hole in the cover should you have some aftermarket cover which is not as factory. This would at least give you an idea to the shifter hole location and possibly where to cut a hole in your floor if adding a manual transmission. The factory hole cut into my floor is not pretty, so I suspect just a basic hole was hacked into the floor knowing that the shifter cover was to be sealed and placed over it along with a console.