I got my John H. White’s American Railroad Passenger Car History finally. I compared the drawings to exisiting HO models and the MDC and Bachmann Old time passenger cars scale out to the right size for OO. There seems to be a percentage shift in size from the late 1860’s to the 1880’s of people size. The later era equipment scales downward to the earlier era. Maybe the increase in food due to the railroad traffic.
A MDC car with OO Langley figures.
I have also updated my 1870’s Why model in OO/HO site with more pictures and better explanation of Why.
http://www.pacificcoastairlinerr.com/1879/why/
Thank you if you visit
Harold