thanks salmon. Your propably right but the F body in the manual must be a scetch from a -68 or -69. The -67 has a front door ventilator and the adjustments screws is not on the same place. I can adjust the rear guide bar + I have a "channel?" so that I adjust a guide bar at the ventilator. Hope you understand, if not just mention where you got lost and I will try to explain in another way.