In my 55 Plymouth, I hooked up the heater core as it was getting cold out and it only lasted about a day and a 1/2 before it went out. The only place that could make one is the brass works and it cost a lot of money and did take a little bit of time, but was well worth it in quality. Now I've got a nice operating heater system. I bought nos motors for the defroster And heater motor while it was down. Just wanted to say thanks to them.
An example of a company based in the states that can design - engineer - manufacture in house while paying a working wage to crafts men and women Respect The Craft @ https://www.thebrassworks.net/ Jim Transporting To Travel Traveling To Share Stories From The Road
Not Brassworks but when I had a local shop redo the heater core a year or so ago it was $150.00. I could have bought an off shore one for a little less but this way I know it's quality.
The Brassworks radiator in my '39 p/u with an 8ba is still working perfectly. Lee at Brassworks took a lot of time and worked with me to insure the 4 inch core would fit. Picked it up in person in 2016 when I went to Trog at Pismo Beach. Got to see his facility. Very impressive.