A few pics of barracuda project.

Awesome job. Those minitubs look like they were factory done that way. I love stuff like that where its modded but done that well it doesnt look like its been touched. Not sure on the rear holes , however you are correct w the seat dimples being bucket seat holes. The outboard holes already have reinforcements for them underneath, the inboard do not. You notice the creases on either side of the inboard holes, thats to mount reinforcing plates on these holes. They are welded to the top of the floorpan on the inside of the car. Seems wierd to me. I would think maybe underneath would have been better, but maybe this way was easier for assembly line purposes, and to keep water from getting in between and rotting out the mount.

i eyeballed a 69 GTS 340 4 speed bucket seat dart a buddy of mine has, got the measurements for the plates off it, and made my own. Installed em the same way his were in the dart. On the top side of the floor pan. The reinforcing plates are pretty inexpensive though. I think you can get em off evilbay for $25 for a set of 4. My pix are a bit fuzzy but i had to enlarge them. If you cant find em, i can make up as set to sell you, or i can send you a cardstock template. They are essentially flat square plates with a hole in the middle, and one corner cut off .

Hope this helps.
Matt

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