I cannot help with suggestions for a replacement torsion style axle
. I know that I had difficulty sourcing a torsion axle from any source about five years ago.
Just a thought, I replaced my original torsion style axle on my 1976 Trillium
with a Dexter leaf spring axle. I've been very happy with the leaf spring axle, it rides very smoothly and was much more cost effective than the torsion- cost including welding new mounts on the trailer frame was about half what a torsion axle would have cost. The axle also has the added benefit of being easily field repairable of needed with easy to find replacement parts.
What I did was purchase a 3500Lb axle, but Mounted it on 2000Lb slipper leaf springs. This gets me the heavier duty axle with larger brakes
, but keeps a smooth ride. A leaf spring axle will raise the ride height slightly vs a torsion axle, but Using slipper style springs minimizes this ride height increase.
The leaf spring axle might not be for everyone, but just wanted to mention that I've had great luck with mine and like it better than my experience with torsion axles.