Both are Kadee standard type knuckles (#5 size), but with differences from there.

The coupler on the Trix (left) started life as a Kadee #4 - it's narrow profile allowed it to slip into the draft gear opening on the pilot. The draft gear "box" was homemade from styrene, and anchored to the pilot with plastic glue in one case and CA in another. The coupler pivot was a small metric screw that I have a stash of (NWSL - worth it.)

The coupler on the Athearn started life as (I think) a #5 with a 233 draft gear box. The box was modified to crear the pilot truck, and anchored with CA.