Eurail Train Schedules

Traveling on a 2nd class Eurail train with a 1st class ticket?
Because of age I will be getting a 1st class ticket for Eurail. I have looked up some train schedules and some say they are a 2nd class train. Does anyone know if I can still ride on it with my 1st class ticket? Or is that for 2nd class tickets only?
Thanks!
Interesting question…
1. To me it looks like 1st Class is good on all trains http://eurail.lwb-online.info/index.php?view=cms_527#pass
whereas, if you only had a 2nd Class Pass, then you would have to pay a supplement on certain “1st Class trains”
2. The Eurail website lists pass 3 or 4 sellers in the USA: http://eurail.lwb-online.info/index.php?view=cms_84 and you could call one of the US sellers and ask them directly.
Good luck & have fun!