[merbesfield]

I don't think you should use PVC? Not sure why you would want to. Here are pics of my old heater tubes. They are basically just a muffler and look like a Cherry Bomb old style muffler. I am thinking the same type deal can be remade by me with tubing, mesh and modern insulation materials. I am going to go to the local muffler shop and have them make me a couple of reducer cones that will reduce the metal exhaust tubing as needed. Not sure how yours worked, but basically these just had a hole cut in the side allowing heat to vent out of the heater slides. They were welded to the edges of the vent opening from inside the car. I will use muffler clamps at either end and then tack weld the nuts so the will not loosen.