I was wondering how picky we get about coupler height? I converted several last night and some are slightly off, some are a good 10% off. Most of what I've converted come out dead on. I'm using Kadee's and I have The Gauge (the coupler height gauge, that is) I think common sense eyeballing it approach will keep me out of trouble, but I thot it was curiouse that the NMRA doesn't seem to like % or +/- tolerances in the RPs I've read. Aviation background makes me a little anal about such matters. Anyone know who makes the rollin' stock that uses a black clip (spring metal) that snaps under the draft gear box? It has a plastic pocket with a plastic stud for the coupler to pivot on. I have several and I 'm short a few clips.