Thank you, Dave!
Yes indeed I feel like I'm stuck guessing without a much clearer photo. And the ORERs I've seen that include this car simply list it as one of (I think) 25 tank cars and doesn't even provide dimensional data.
Thank you for the recommendations! I do have the lot number (#6589), so I'll track down Nick Fry and see if he can help.
PS: I also got an email from Richard Townsend with a link to an antique Virginia Dare tray - thanks a lot, Richard!