Reply to "Non-Magnetic Milk Can Help"

I too have been working with the Lionel milk car (3662).  I did a little experimenting and tried different voltage settings to operate the car.  Seemed to work best at around 8.5 volts......however, sometimes some of the cans would still fall over!......but it certainly looks more realistic then at the 10 volts from my Z4000 transformer. I am using Atlas track with their #6097 accessory rail kit.  It appears to sit at a perfect height with the platform, as the doors of the car just clears the platform.  Anyone know what diode would work best to reduce the voltage down from 10 volts to 8.5 volts?  Thanks