If you look at the link from bfdinardo you will see that the tubing I purchased was online. I could not source anything locally. Oldmics has a link for a very nice insert because it has the hump on the end to help seal the heater hose to the tube. I bought a 3 foot length or so and it was about the price from Napa for just the one insert. The piece I bought from online metals had a much thicker wall than original. Most of the reason these tubes need to be replaced is because the wall just did not hold up to corrosion... but let's be honest, I highly doubt that anyone thought back in 1955 that in 2019 there would be so much demand for these original parts.
try onlinemetals.com