I'm still tinkering with them. They never seem to get completely done.
They are all basically the same. The mountings to the car is what vary. Some use a single spine down the middle, others a twin spine.
I don't know the detail of the "original Mindtrain" but I suspect that the ends were securely fastened into the decklid with either rivets or button head screws and riv-nuts?
I only saw the Mindtrain in person once, I didn't own a Pantera then and didn't think to look for those details but I think they are single spine, down the middle so that makes the end mountings more important.
I have a picture of the Pantera that Jeff Burgy once owned with them installed. That's the car that I saw them on.
Over the rear decklid tends to be a dead air area so they aren't particularly susceptible to flying away but I don't know of anyone who ever tested them at very high speeds.