The SPCRR found fragments of Miller Hook couplers at several places including Sumpter. And in Michigan... but also parts on the coach held by Orange Empire... drawings at CSRM,
The Nevada State Railroad Museum created a copy based on patent drawings... We found SP drawings for a different version... We made a set for SPng 1010...
NSRM has patterns for standard gauge, Miller Patent style... SPCRR has patterns for narrow gauge SP style...