There once was a movement to have mechanical standards for 3 rail equipment but it kind of fizzled out. This was maybe around 15-18 years ago (I think). There was no interest in it I guess because most toy train enthusiasts, who make up the bulk of O gauge, don’t care. Which explains why the manufacturers are all over the place. They know most enthusiasts aren’t going to complain. I started out in 3 rail and not only did I have one coupler that wasn’t the same height I had another coupler (from K Line) that wouldn’t even close against another manufacturer’s coupler. That was very frustrating.
Other than bending the coupler like someone said how would you adjust the height of a coupler that is permanently fixed to a truck? I have never seen any of the 3 rail Lionel type couplers that have some sort of a height adjustment.
