There isn’t a furnace or boiler made in 1955 that is worth keeping in these days of costly fuel. The unit has been throwing away at least 40% of the fuel for half a century.
If you want to fix it, it’s a good idea to give the make and model instead of just the serial number. You give no clue why you need a flue instead of just cleaning it up and tuning it up.
http://www.heatpro.us energy businessmen’s knowledge
Yes, you really have to find out the MAKE and MODEL to get good answers. There IS more than one machine made.