George, I recently found the sheet in my '70 KC built car. It was inside the front seat back. We pulled the cover to redo the seat and it was hog ringed to the springs. Good luck! Jeff
I was trying to remember that as I typed the last post. I really don't remember for sure. I think it was the driver's, but not positive. Sorry I couldn't be more help, Jeff
My '67 GS 400 conv was built in Kansas City, the car has been completely apart but no build sheet was found