One year and one month. The car is a dailydriver.
Before I installed them I even gave them a coat of paint for protection.

Here's the entry on my site when I installed them;
http://www.bigblockmopar.nl/2013/11/1973-dodge-dart-1-torsion-bar-upgrade/

We did have our first night of freezing temps the day before, maybe they just couldn't handle the cold... lol

I do need to say the car sees a lot of speedbumps everyday here on my daily commutes. Most are fairly 'smooth ramped' speedbumps but I also encounter 3 concrete short curved bridges 2 or 4 times a day which have a ridge on the ramps that can be considered rough if you don't slow down enough.