I decided to make these up after reading a thread about live axle handling and they were mentioned. At the time, I needed a project so decided to give them a try and see if they made a difference.
I ordered a pair of smaller 3/8" spherical bearings for the car end, a pair of larger 1/2" bearings for the axle end. I also got a couple of lengths of tubing and threaded inserts to suit the 1/2" bearings. I ordered the 1/2" bearings with left hand threads so I could adjust the length of the radius arms easily, along with matching locknuts. I then got a friendly engineering company to shorten the tubes and to make up a couple of threaded inserts to suit the 3/8" bearings and the tube diameter. The final result was then powder coated in black to protect it all.
Fitting the new arms was a simple case of unbolting the standard items and the offering up the new ones with he old ones still fitted. It was at this point that I adjusted the length of the arms to match the old ones and then swapped them over on the car.
My initial drive showed that the car really felt a lot better over a bumpy road and I was able to drive comfortably 7-8mph faster (on a national speed limit road).
I was very pleased with the improvement that the new radius arms gave, and I ran them for the remainder of the year. They were on the car when we went over to Spain and during the trip I started to notice a slight knocking/rattling noise when traveling over bumps when traveling at around 30mph. When I returned home I had a good poke around at the back of the car and found that both of the 1/2" bearings had developed some play and it was this that I could hear over the bumps. I swapped back to the old radius arms and went for a test drive and the noise was all gone. I found some higher specification bearings and had to wait a while for them to arrive. I swapped them back over again and ran them again but this time they lasted even less time before I heard the knocking noise return. The old originals were swapped back on and they will remain on the car as the high specification bearings are too expensive to keep trying.
Worth a try.

Collection Of Parts	Bearing fitted	Fitted to Car (with rubber boots)