B T5 heater tubing to front defroster?

[Walter Piescik]

Does anyone know where to find any drawings of the heater tubing from the heater duct in the longitudinals up to the front defroster?

The air travels up through the lower part of the A Pillar, but that particular corner of my car suffered some butchery in the 70s, and there is no tubing run up there...the air just flows up through the A pillar.

It looks like there is supposed to be a steel tube that runs up through there based on some pictures of NOS parts that Peter from Restoration Design kindly provided me. Perhaps there are factory drawings available somewhere?