Someone was pretty close to some advanced ET requirements then. The double bar running behind the seat and all the x braces in the footbox area appear to be right. What I don't understand is the square tube behind the shoulder hoop, unless is it part of the jig that was being used. The cage angle may be an issue but Diamond Racecars lay their bars back lack that. I am going to send a message to the seller to get some history on the car. You got me curious now. 8)