Looking a long time for a duct,has anyone made one? I wonder if they were make at the factory or contacted out and if so what company would it be.Maybe some one out there knows.
Finding one of these in good condition may be a long drawn out process...if one was fortunate enough to luck upon one, and it appears solid..I would recommend that it be sealed with an epoxy for reinforcement prior to trying to remove it. I you get lucky and do this first and are able to remove it intact..you can then treat the inside of the duct in same manner and maybe save the unit
My 54 was one of low mileage but the damp humid weather of the south made the duct not salvageable as it had deteriorated. Long story short, I fabricated mine out of sheet metal in the best copy possible of the original, a trimmed down gallon paint can modified for the duct to attach made the fan housing..took a bit but really works well and looks good..utilized the original clamps and attachments
as an added note..this did require welding very thin sheet metal..possible using .030 copper coated steel weld wire (MIG wire) and an 000 tip on my ocy/acet torch..
bigaadams has offered the best solution for your problem. I have seen this done with a large coffee can too. I do not know what these things were made of originally but they surely were not made to last.
Some 53-4s have a duct made of similar material under the dash. I have a good one of these anyone can have if they pay the freight. dp