There is a spot drilled into the buffer beam to show where the 16mm standard buffer height is. The buffer I give with the model does not have to be used. So you can simply use the spot for height reference and fit any coupling you like.
As for robustness, I wouldn't use it as a football, but I've been running everything you see on my site since it was made and never broken anything. I've also never been asked for replacement parts from my customers.
I did once watch a brand new square tanker I'd just made roll off the work bench and smash into the concrete floor three foot down !!

The only thing that broke off was the buffer beam. One nice clean snap, very quickly fixed with super glue. A super glue joint on this resin is stronger than the resin itself.
Hope that helps.
Rob
