Three quarter size Sharon type coupler castings with all the working parts were recently purchased from ABC NACO Technologies but that company was purchased by Matrix Metal and is now called Foundry Richmond, at Richmond, Texas.
[www.supplierworldwide.com]
We used Drawing #0352304 for 3/4 size Sharon 10 couplers. I am sorry I can not say if they have a 1/2 size for the Sharon but you can ask them at phone 281-342-5511. One contact name we have listed is Al Kinnard of Matrix Metal.
Hope this answers some need for a source to make new couplers for 2' and 3' gauge cars. The WW&F got two coupler in our same order that was split.