I installed a competition Engeering 8 pt cage in my 67 coupe. You just need to buy the 67 mustang main hoop and a strut kit. And if you want to retain your back seat as I wanted to you also need to buy optional Formed Rear Struts.
Summit Racing Part numbers:
Main Hoop / Strut Kit: CEE-3039 - $159.88
Formed Rear Struts: CEE-3185 - $46.99
It takes queit a good amount of custom tube notching and fabrication for the install into the vehicle. I spent a long Saturday with a helper to install mine, We constantly were setting seats into place ect checking the clearances on everything...It just takes time.
Also you need ot have sub frame connectors as the Struts that come down twards the center of the car are supposed to be welded to your subframe connectors, this is what adds to your torsional rigidity of the car.
To make the back seat more user friendly I also left out the "side impact member" (I think thats its name). This is the horizontal member that crosses behind the seats, it is there to for when you get T-boned. It would make it extremely difficult if not impossible to get into the rear seat...The reason I installed my cage was to add rigidity to my unibody upon my bodyman/painter's request as there was already considerable stress damage behind the windows. So I figured leaving out this member wouldnt be an issue.
PS: sorry the carpet is kinda in the way, I still need to trim it...Can anyone see the attachemnt? I get "No input file specified" ??? I get that on all attachments actually!!
