FWIW - J&B (the distributor for Sun trikes) does stock delta trike rear axle assemblies - your bike shop, if it deals with J&B should be able to order one for you. Just be sure it is a hi-ten steel assembly. A good welder should be able to cut off the existing rear assembly and glue the new one on. Bonus - you would get an assembly that can use disc brakes, which you would have to buy, and you would also have to buy appropriate hubs (the disc rotors mount to the wheel hubs) laced to appropriate wheels. You would still have a very, very tall trike which will make for instability.