I finished my "52" last spring with a complete overhaul of the drive line. After only about 500 miles something felt wrong. Found my new u-joint failed. There must have been a design problem as a new part could not be purchased from any supplier. I was able to find someone on e-bay that had new original u-joints. I purchased mine for $75 but when this seller found that the replacement u-joints could not be found his price went to around $175.
Here is a picture of the new failed part and the new original part. You can see where the reproduction failed. The original is all steel, much better design, and still running fine after 2500 miles.