1965-66 GT350 Concourse Headers We have completed retooling from scratch to produce our councourse headers. Backorders are being filled and we are ready to add new orders to the list. Our jigs were built and checked with 2 set sof original headers and a set of our previous headers. 2 sets of NOS headers were also studied. The flanges are angle ground for head bolts and great efford went into making sure the port shape at the head flange is correct.